Drafted by E Segerdell, JB Bowes, N Pollet, and PD Vize BMC Dev Biol. 2008 Sep 25;p.8-92 (PMID:18817563)
XAO v2.0 update VG Ponferrada, CH James-Zorn, E Segerdell, W Dahdul Sep 2011
Anatomical structure/expression stops being viable, obvious or of utility at this developmental stage.
Primary germ layer that is the outer of the embryo's germ layers and gives rise to epidermis and neural tissue.
Surface structure that has an important role in tadpole locomotion. It starts to develop along the trunk and tail of the embryo at the tail bud stage and continues to grow until the start of metamorphosis when it begins to regress. It consists of flattened epidermal cells elevated into a keel-like structure by a supporting core of mesenchyme and extracellular matrix.
A thick plate of cells derived from the neural ectoderm in the head region of the embryo that develops into the olfactory region of the nasal cavity.
The saccular invagination of ectoderm from which the vertebrate inner ear develops.
Transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina.
Sensory membrane that lines the posterior chamber of the eye and functions as the immediate instrument of vision by receiving the image formed by the lens and converting it into chemical and nervous signals which reach the brain by way of the optic nerve.
Organ that is a component of the central nervous system and is responsible for the coordination and control of bodily activities and the interpretation of information from the senses. It appears when the neural tube segregates in forebrain, midbrain, and hindbrain at NF stage 22. The general pattern of the brain has been mainly established at NF stage 28. Yolky material is consumed and the fibre tracts and later the commissures develop. In general all of its parts are well developed at NF stage 53 and later development consists mainly of growth and some further cytological differentiation. In the period of metamorphosis only topographical changes take place.
The part of the brain that is the anterior of its three primary divisions and that includes the telencephalon and diencephalon.
Part of the forebrain consisting of paired olfactory bulbs and cerebral hemispheres.
The more posterior and ventral of two forebrain neuromeres, the other being the telencephalon; major derivatives are the eye vescile, the brain pretectal region, the thalamus, hypothalamus, and epithalamus (including the habenula and epiphysis).
Middle part of the brain composed of the optic tectum and penducular region.
The part of the brain that is the posterior of its three primary divisions.
The part of the brain that is the morphological boundary between the midbrain and hindbrain and that is the location of an organizing center which patterns the midbrain and hindbrain primordia of the neural plate.
An endocrine gland, located ventral to the diencephalon, that secretes hormones that regulate many other glands.
Portion of tissue that is the precursor to the gonads.
Elongated, approximately cylindrical part of the central nervous system that lies in the vertebral canal and from which the spinal nerves emerge.
Organizing center located at the dorsal midline of the neural tube that influences the development of the nervous system, controlling the specification and differentiation of dorsal neuronal cell types.
Surface structure that consists of the external membranous integument of the animal.
The most posterior of the population of migratory cells of the cranial neural crest, forming the branchial arch 3 and 4.
The outer epithelial layer of the external integument of the body that is derived from the embryonic epiblast.
The outermost layer of the epidermis, the multilayered epithelium derived from the ectoderm.
Thin membrane enclosing and immediately adjacent to the ovum. Produced in the ovary. The membrane enveloping the egg or oocyte; lies immediately outside the plasmalemma; formed while the oocyte is in the ovary; separates from the egg to form the fertilization membrane.
Cell type that has motile cilia and populates the skin of the embryo, arranged in the surface layer of the non-neural ectoderm in an ordered distribution.
An anterior thickening of the sensorial layer of ectoderm, just above the cement gland. The hypophyseal layer separates from the stomodeal layer at NF stage 29&30, and when contacted by a protrusion of the foregut, the stomdeal layer will rupture to form the mouth opening at NF stage 39-40.
A simple mucus-secreting structure that is positioned at the front of the embryo, attaches the newly hatched embryo to a support before the hatchling can swim well or feed, and marks the anterior-most dorsal ectoderm.
A Y-shaped array of unicelluar glands on the top of a head, the open end of the Y faces anteriorly, that secrete an enzyme that dissolves or weakens the egg jelly and facilitates hatching. Presumptive cells of the hatching gland are present by the end of gastrualtion ( NF stage 12.5) and differentiated cells start to form after neurulation is complete (NF stage 21).
Cell resulting from the fusion of male and female gametes at fertilization.
Sensorial layer of blastocoel roof ectoderm.
Superficial layer of blastocoel roof ectoderm.
The anterior most third of the embryo, from the development of the head outgrowth at NF stage 21.
A distinct layer of the epidermal cells beneath the outermost layer of epidermis, the multilayered epithelium derived from the ectoderm.
Embryonic ectoderm that gives rise to nervous tissue.
The portion of neural plate anterior to the mid-hindbrain junction.
The portion of neural plate posterior to the mid-hindbrain junction.
A group of embryonic cells that loosen and separate from the neural plate and surrounding epidermis during neurulation and migrate to give several different lineages of adult cells.
The thickening of the epithelial layer of the ectoderm, with corresponding dark pigmentation, on the anterior dorso-ventral surface of the embryo.
Primary germ layer that is the middle of the embryo's germ layers.
Principal unpaired, median artery of the trunk, extending into the tail as the caudal artery.
The paired main vein, departing from the sinus venous, the fused heart primordium, it runs posteriorly down length of the embryo.
A longitudinal flexible rod of cells that in the embryo forms the supporting axis of the body. It degenerates, beginning anteriorly, at NF stage 46. Its posterior portion is greatly reduced by NF stage 55 and the entire structure is gone by NF stage 65.
Transient structure that lies immediately ventral to the notochord in the embryo, likely required for the formation of the dorsal aorta. A slight depression marks the future hypochord at NF stage 20 and its segregation from the dorsal endoderm begins at NF stage 24. It progresses from anterior to posterior and is complete by NF stage 28. At NF stage 32 it is present as a dorso-laterally flattened ribbon of yolk-laden cells. It degenerates by apoptosis and by NF stage 43 is no longer detectable as a distinct structure.
Unsegmented field of paraxial mesoderm present posterior to the most recently formed somite pair, from which somites will form.
Any of the approximately 45 bilaterally paired blocks of mesoderm cells, lying on either side of the notochord and neural tube, and forming sequentially starting at the head during development of the embryo. Together they give rise to the axial skeleton (from the sclerotome), associated musculature (from the myotome), and dermis (from the dermatome).
The opening of the pronephros into the body cavity.
Internal, blood-pumping circulatory system organ ultimately composed of three chambers (two atria and one ventricle) and occupying a ventral position within the chest of the mature tadpole/frog.
The middle layer of the heart, consisting of cardiac muscle.
Part of the heart composed of thin serous membrane and endothelial tissue, that lines the interior of the heart.
Region located on the ventral surface of the developing embryo that is a site of hematopoiesis and that is analogous to the yolk sac blood islands of higher vertebrates.
Belt-like region of presumptive mesoderm at the equator of the late blastula.
Marginal zone that is a key embryonic tissue region of the early gastrula stage embryo and that houses the Spemann-Mangold organizer.
involuting marginal zone mesenchymal layer
involuting marginal zone epithelial layer
Cell type that is first to migrate inwards at the blastopore during gastrulation.
The region from which the forelimb develops, first recognizable at NF stage 48, and distinct by NF stage 49.
The region from which the hindlimb develops, first recognizable as a slight concentration of mesenchymal cells dorsal and lateral to the anal tube at NF stage 43. The epidermal layers thicken dramatically through to NF stage 48, and become vascularised by NF stage 49.
Mesoderm between somite and lateral plate. Traditionally thought to give rise to the urogenital system.
The region at the periphery of the retina where retinal stem cells are located. It is spatially ordered with respect to cellular development and differentiation, with the youngest and least-determined stem cells closest to the periphery, the proliferative retinoblasts in the middle, and postmitotic cells at the central edge.
Primary germ layer that lies remote from the surface of the embryo and gives rise to internal tissues such as gut.
The cavity of the gastrula forming a primitive gut. At NF stage 20-21 its wide canal becomes dorso-ventrally compressed and narrowed in the future trunk region so that a subdivision into a foregut, a midgut and a hindgut with protruding endodermal mass becomes manifest.
The layer of cells forming the ventral surface of the archenteron space of the embryo.
The layer of cells forming the dorsal surface of the archenteron space of the embryo.
Sensory system that has as it parts the sense organs that detect vibrations carried through water, develops during late tailbud stage, and persists in the adult bearing elaborate dorsal and ventral components. It develops from a specialized series of dorsolateral ectodermal placodes named lateral line placodes.
One of a series of bony or cartilaginous arches that develop in the walls of the mouth cavity and pharynx of the embryo.
The pharyngeal arches (which develop into the branchial arches) are anlage for a multitude of structures. Each pharyngeal arch has a cartilaginous stick, a muscle component which differentiates from the cartilaginous tissue, an artery, and a cranial nerve. Each of these is surrounded by mesenchyme. Arches do not develop simultaneously, but instead possess a \"staggered\" development.
Anatomical system that has as its parts the heart and blood vessels.
An out-pocket of thickened ventral foregut epithelium adjacent to the developing heart. Its anterior portion gives rise to the liver and intrahepatic biliary tree, while the posterior portion forms the gall bladder and extrahepatic bile duct.
First of the pharyngeal (endodermal) evaginations between the visceral arches from which the Eustachian tube is derived; pouches 2-4 open as gill slits.
Middle subdivision of the digestive tract. The midgut is the portion of the embryo from which most of the intestines develop. After it bends around the superior mesenteric artery, it is often referred to as the \"midgut loop\". It comprises the portion of the alimentary canal from the end of the foregut at the opening of the bile duct to the hindgut, about two-thirds of the way through the transverse colon.
Posterior subdivision of the digestive tract. The posterior part of the alimentary canal, including the large intestine and cloaca.
Rapidly proliferating mass of cells at the caudal extremity of the embryo. Its formation is reflected in a caudal carving of the posterior portion of the archenteric canal at NF stage 22. With its further outgrowth, the postanal gut primordium becomes stretched. Its lumen is in broad communication with the hindgut at NF stage 25.
The anterior limit of the neurenteric canal, which connects the post-anal gut with the central canal of the spinal chord. It is formed from a population of cells derived from the dorsal lip of the late gastrula, and has been shown to be important in tail development.
Portion of tissue that consists of the precursors of the pronephric glomus or glomerulus; derived from the medial portion of the pronephric intermediate mesoderm.
Cell type that is involved in the reproduction of the organism.
Anatomical entity that comprises the animal in the early stages of growth and differentiation that are characterized by cleavage, the laying down of fundamental tissues, and the formation of primitive organs and organ systems.
Any of the tubular branching vessels that carry blood from the heart through the body.
Any of the tubular branching vessels that carry blood from the capillaries toward the heart.
Any of the smallest blood vessels connecting arterioles with venules.
Anatomical system that has as its parts the organs involved in breathing in respiration (breathing).
An elongated tube which carries air to and from the lungs.
Either of two organs which allow gas exchange absorbing oxygen from inhaled air and releasing carbon dioxide with exhaled air.
The primary respiration organ in some species of tadpoles, whose function is the extraction of oxygen from water and the excretion of carbon dioxide. The microscopic structure of a gill is such that it presents a very large surface area to the external environment. Gills usually consist of thin filaments of tissue, branches, or slender tufted processes which have a highly folded surface to increase surface area. A high surface area is crucial for effective gas exchange.
A passage of airway in the respiratory tract that conducts air into the lungs.
Anatomical system that consists of the blood and blood forming tissues.
Flexible tissue found in the hollow interior of bones. In adults, marrow in large bones produces new blood cells.
The fluid that circulates in the heart, arteries, capillaries, and veins carrying nourishment and oxygen to and bringing away waste products from all parts of the animal.
Anatomical system that has as its parts the organs devoted to the ingestion, digestion, and assimilation of food and the discharge of residual wastes.
Tube that connects the pharynx to the stomach. At NF stage 57 it is a straight tube, round in cross section, and starting from the pharynx runs backward along the dorsal side of the abdominal cavity. Its lining consists of a columnar glandular epithelium with mucus secreting cells. It is thrown into longitudinal folds.
Internal organ that is the dilated portion of the alimentary tract situated between the esophagus and the beginning of the duodenum. It produces gastric juices involved in the breakdown of food.
Portion of the alimentary canal bounded anteriorly by the pyloric sphincter and posteriorly by the cloacal sphincter.
Organ which secretes bile and participates in formation of certain blood proteins.
Duct that carries bile from the liver to the small intestine.
A small organ of the alimentary system that aids mainly in fat digestion, and concentrates bile that is produced by the liver.
Internal gland organ with distinct tissues with different endocrine and exocrine functions. Its rudiment has three parts, one dorsal and two ventral primordia. The ventral can be first detected at NF stage 37/38. The dorsal is clearly segregated from the duodenal wall by NF stage 39. At NF stage 40 the right and left primordia have fused just above the gasto-duodenal vein. At NF stage 42 blood vessels penetrate into the crevices between the pancreatic acini making them more conspicuous.
Pancreatic tissue composed of acinar epithelial cells and ductal epithelium that manufacture the proteolytic enzymes and bicarbonate required for digestion.
Serous membrane that forms the lining of the abdominal cavity or the coelom. It covers most of the intra-abdominal organs, supports the abdominal organs, and serves as a conduit for their blood and lymph vessels and nerves. It is composed of a layer of mesothelium.
Anatomical system that has as its parts the organs concerned with the production and excretion of urine and those concerned with reproduction.
Organ that is the definitive adult kidney. It replaces the earlier pronephros, which degenerates as the mesonephros becomes functional in feeding stage tadpoles.
Anatomical system that has as its parts the organs concerned with reproduction.
Anatomical system that has as its parts the organs concerned with the production and excretion of urine.
Anatomical structure consisting of long narrow duct which carries urine from the kidney to the urinary bladder.
A tuft of capillaries found in a Bowman's capsule in which waste products are filtered from the blood and urine formation is initiated. Paired highly vascularized structures of the pronephros, responsible for blood filtration.
The organ that collects urine excreted by the kidneys before disposal by urination.
The organs of the male reproductive system.
The organs of the female reproductive system.
Reproductive organ that produces and releases sperm.
Anatomical system that consists of the glands and parts of glands that produce endocrine secretions and help to integrate and control bodily metabolic activity.
Structure that is made up of islet cells that produce insulin, glucagon, and somatostatin.
An unpaired glandular organ subdivision attached on the midline near the posterior and habenular commissures of the epithalamus.
A two-lobed endocrine gland, located next to the trachea, and producing various hormones, such as triiodothyronine and calcitonin.
Anatomical structure of largely lymphoid tissue that functions in cell-mediated immunity by being the site where T cells develop.
Either of a pair of complex endocrine organs near the anterior medial border of the kidney consisting of a mesodermal cortex that produces glucocorticoid, mineralocorticoid, and androgenic hormones and an ectodermal medulla that produces epinephrine and norepinephrine.
Situated along the perimeter of the adrenal gland, the adrenal cortex mediates the stress response through the production of mineralocorticoids and glucocorticoids, including aldosterone and cortisol respectively. It is also a secondary site of androgen synthesis. The perimeter region of the adrenal gland, the site of steroid synthesis.
Part of the adrenal gland, located at the center of the gland, being surrounded by the adrenal cortex. It is the innermost part of the adrenal gland, consisting of cells that secrete epinephrine, norepinephrine, and a small amount of dopamine in response to stimulation by sympathetic preganglionic neurons. Composed mainly of hormone-producing chromaffin cells, the adrenal medulla is the principal site of the conversion of the amino acid tyrosine into the catecholamines adrenaline (epinephrine), noradrenaline (norepinephrine), and dopamine.
An organ specialized for secretion of parathyroid hormone. It controls the amount of calcium in the blood and within the bones.
Anatomical system that provides locomotion and physical support to the organism.
The hard form of connective tissue that constitutes the majority of the skeleton.
A type of dense connective tissue that is composed of specialized cells, chondrocytes, that produce a large amount of extracellular matrix.
Anatomical cluster that consists of two or more adjacent bones or cartilages, which may be interconnected by various types of tissue.
A body tissue consisting of long cells that contract when stimulated and produce motion.
A fibrous, strong, connective tissue that connects muscle to bone.
A type of muscle used to create movement, by applying force to bones and joints.
Involuntary muscle tissue consisting of uninucleate spindle-shaped fibers.
Anatomical system that consists of the skin and its appendages.
Anatomical system that has as its parts the brain and spinal cord, nerves, ganglia, and parts of the receptor organs and that receives and interprets stimuli and transmits impulses to the effector organs.
One of the two major divisions of the nervous system. Its nerves connect the central nervous system with sensory organs, other organs, muscles, blood vessels and glands.
The organ of sight (visual apparatus), almost spherical in shape. At the end of development (NF stage 66) the eyes bulge out of their orbital capsules near the lateral edge of the dorsal side of the head.
The transparent front part of the eye that, together with the lens, refracts light.
A general term for the whole eye, or eye ball, of an organism.
A clear mucous membrane consisting of cells and underlying basement membrane that covers the sclera and lines the inside of the eyelids. It is made of epithelial tissue.
The opaque, fibrous, protective, outer layer of the eye containing collagen and elastic fiber.
A membrane in the eye, responsible for controlling the amount of light reaching the retina.
Circumferential tissue inside the eye composed of the ciliary muscle and ciliary processes.
Lateral neurogenic placode region positioned dorsal to the epibranchial placodes, and include the lateral line placodes, the otic placode and the trigeminal placode.
The combination of structures that form the ear and function to transmit vibrations and permit hearing.
Labyrinthine anatomical cluster that comprises sensory endorgans specialized for vestibular, auditory, and acoustico-vestibular sensation.
A major structure of the inner ear, ventral to the utriculus. Two small pouches extend from it- the papilla basilaris, and the papilla amphibiorum. The sacculus functions in the detection of sound.
Fluid-filled ducts that loop from the utriculus in the inner ear, and help detect movement and maintain balance.
The small, oval, bony chamber of the labyrinth. The vestibule contains the utricle and saccule, organs which are part of the balancing apparatus of the ear.
Pigmented, smaller blastomere of the animal (upper) hemisphere of the cleaving embryo.
In developmental biology, the embryo is divided into two hemispheres: the animal pole or hemisphere and the vegetal pole or hemisphere. The animal hemisphere is the actively dividing hemisphere of the embryo, opposite the vegetal hemisphere, and is pigmented dark brown.
A type of mesoderm that lies along the central axis, under the neural tube, and gives rise to the notochord.
The first appearance of the antomical space that will become the blastocoel.
The dorsal surface of the blastocoel, the cavity of the blastula.
The opening of the archenteron to the exterior, marks the point of orgin of the archenteron and the caudal end of the embryo.
Portion of tissue that contains cell bodies of neurons and is located outside the central nervous system.
The thin membrane or integument, which is stretched over a cartilaginous annulus in a drum-like manner, and forms the outer ear, receiving airborne vibrations and functions in hearing.
The narrow tube connecting the middle ear with the pharynx, through which air flows to equalize pressure on either side of the tympanic membrane.
Any of the three tiny bones of the inner ear (columella or stapes, the sacculus and the utriculus) suspended in the otic capsule.
The part of the nervous system that consists of the brain and spinal cord, to which sensory impulses are transmitted and from which motor impulses pass out, and that supervises and coordinates the activity of the entire nervous system.
Spatial descriptor for the outermost or superficial layer of an organ, such at the cerebral cortex or adrenal gland cortex; or the outer most layers of the oocyte.
A layer of skin between the epidermis (with which it makes up the skin) and subcutaneous tissues, and is composed of two layers, the papillary and reticular dermis.
An internal or external body part or prolongation that projects from, and is attached to, an organ or the main body of an organism.
Somitic compartment that is a precursor of dermis, the cells of which become arranged in a single layer that blankets the myotome, possibly continuously (unsegmented) across somites.
Invagination of thickened epithelium near the hindbrain that gives rise to a spherically shaped ear vesicle.
The ectodermal precursor of the trigeminal ganglion. The profundal and the trigeminal ganglia are separate distally but fused at their proximal end as they condense around NF stage 24.
First trace of the future visual apparatus. The eye primordia forming antero-lateral evaginations of the closing neural tube are originally massive formations into which only a slit-shaped extension of the neural groove penetrates at NF stage 18. At NF stage 19 they clearly segregate from the anterior portion of the neural tube.
The optic vesicle is the evagination of neurectoderm that precedes formation of the optic cup. Portion of tissue that is comprised of neuroepitheium which has pinched off from the anterior neural keel and will form the optic cup.
Cell type that forms a layer within an ovarian follicle that surrounds the oocyte.
The anterior part of the alimentary system, from the mouth and esophagus to the duodenum at the entrance of the bile duct. Structures of the foregut are: esophagus, stomach, duodenum, liver, gall bladder, and pancreas. The spleen is located in the foregut region, but is not a gut organ.
A zone found in the cytoplasm of the egg cells which contains determinants that will give rise to the germ cell lineage. As the zygote undergoes mitotic divisions the germ plasm is ultimately restricted to a few cells of the embryo. These germ cells then migrate to the gonads.
The nucelus of the oocyte, it is enclosed in a nuclear envelope and contains neucleoplasm, in which the chromosomes and extranucleoli are embedded. It breaks down as the oocyte matures, being no longer visible by the first meiotic metaphase.
Two migratory heart primordia that move ventrally during the course of neurulation, and whose fusion begins at the ventral midline at NF stage 16.
The first part of the small intestine. At the junction of the stomach and the duodenum the alimentary canal is inflected. The duodenum first goes anteriorly for a short distance, turns dorsally, and eventually caudally, thus it is a U-shaped structure with two horizontal sections (a ventral and a dorsal one).
The final section of the small intestine.
The pancreatic duct and common bile duct enter the descending duodenum, commonly known together as the hepatopancreatic duct.
A thickened portion of ectoderm which serves as the precursor to the lens.
The posterior cardinal vein returns blood from the trunk and drains into the duct of Cuvier via the pronephric sinus.
The last portion of the digestive system, it extracts water and salt from solid wastes before they are eliminated from the body.
The posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts.
Second of the pharyngeal (endodermal) evaginations between the visceral arches from which the Eustachian tube is derived; pouches 2-4 open as gill slits.
The median dorsal longitudinal groove formed in the embryo by the neural plate after the appearance of the neural folds.
A region of embryonic ectodermal cells that lie directly above the notochord. During neurulation, they change shape and produce an infolding of the neural plate (the neural fold) that then seals to form the neural tube. At NF stage 11.5 is the first indication of neural plate within the sensorial layer of ectoderm. It extends to near the animal pole by NF stage 12.5 and the entire plate is faintly delimited by NF stage 13.
Third of the pharyngeal (endodermal) evaginations between the visceral arches from which the Eustachian tube is derived; pouches 2-4 open as gill slits.
Fourth of the pharyngeal (endodermal) evaginations between the visceral arches from which the Eustachian tube is derived; pouches 2-4 open as gill slits.
Fifth of the pharyngeal (endodermal) evaginations between the visceral arches.
The developing female gamete, the differentiation of which is classified into six stages: I (pre-vitellogenic), II (early vitellogenic), III (mid-vitellogenic, formation of pigment), IV (polarization along animal-vegetal axis), V (late vitellogenic), and VI (post-vitellogenic, appearance of equatorial band).
Either of paired female reproductive organs involved in production of ova and female sex hormones.
Area of mesoderm at either side of the midline embryonic notochord that, on segmentation, forms the paired somites.
Portion of tissue that consists of the mesenchymal precursor to the pronephric kidney and that begins to separate from the intermediate mesoderm at NF stage 21 and epithelializes by NF stage 30.
Sixth of the pharyngeal (endodermal) evaginations between the visceral arches.
Layer of lateral plate mesoderm that forms the future body wall; it underlies the ectoderm.
An auxiliary olfactory sense organ involved in the detection of pheromones.
splanchnic layer of lateral plate mesoderm
Layer of lateral plate mesoderm that forms the circulatory system and future gut wall; it overlies endoderm.
The internal nasal passages, aperture or cavity in the roof of the buccopharynx.
When the marginal zone mesoderm undergoes involution, where the marginal zone contacts the vegetal base.
Unpigmented, larger blastomere of the vegetal (lower) hemisphere of the cleaving embryo.
Pharyngeal (endodermal) evaginations between the visceral arches from which the Eustachian tube is derived; pouches 2-4 open as gill slits.
A hole located in the center of the iris of the eye that allows light to enter the retina.
The three distinct placodal areas, which develop from the posterior placodal area, and lie ventral to the otic placode and dorsocaudal to the pharyngeal clefts, and contribute to the sensory ganglia and cranial nerves.
The structure that is the basic functional unit of the pronephros.
Portion of the pronephric tubule which is just posterior to the early proximal (straight) tubule.
The structure that is the basic functional unit of the kidney.
A blastocoel forms during embryogenesis when a zygote (a fertilized ovum) divides into many cells through mitosis. The blastocoel is the cavity of the blastula, a closed space which is invaded by early mesenchyme and later obliterated by the enlarging archenteron.
The portion of endoderm between dorsal and ventral blastopore lips, and extending towards to the blastocoel.
In developmental biology, the embryo is divided into two hemispheres: the animal pole or hemisphere and the vegetal pole or hemisphere.
Spatial concept denoting the back or upper surface of the body.
Spatial concept denoting the underside or lower surface of the body.
Spatial concept denoting extension relatively far inward.
Spatial concept pertaining to being situated at or extending to the side.
A localized ectodermal thickening that develops by apicobasal elongation of cuboidal cells in the inner layer of the ectoderm in the head of the embryos, and is involved in formation of sense organs.
Organizing center consisting of a small group of cells located at the ventral midline of the neural tube that influences the development of the nervous system, governing the specification of neuronal cell types and directing axonal trajectories.
The anterior U-shaped portion of the neural folds, the two longitudinal dorsal ridges, caused by a folding up of the ectoderm, that make their appearance on either side of the middle line of the early neural embryo.
Portion of the middle of the three primary germ layers of the embryo that resides on the periphery of the embryo, splits into two layers enclosing the intra-embryonic coelom, and gives rise to body wall structures.
Any of the transient, degenerating occipital somites.
Somitic compartment that is a precursor of muscle.
The inner layer of the pericardium that is in contact with the surface of the heart.
Properly called a glomus as it extends over multiple body segments.
The filtration unit of the pronephric kidney. A glomus is a glomerulus that spans more than one body segment. It is the vascularized filter of the pronephric kidney. Blood is filtered through the glomus and the filtrate deposited into the coelom early in development, or the nephrocoel later in development. The Xenopus glomus contains podocytes with well developed foot processes that are anatomically indistinguishable from the podocytes of adult glomeruli. The two glomera are linked via a narrow bridge called the glomeral nexus.
Trunk portion of the neural crest. The anterior and middle regions of the neural crest segregate at NF stage 16, while the posterior portion forms at NF stage 17. The neural crest of the trunk region that give rise to peripheral ganglia, and are migratory.
Derivative of ectodermal thickening ventral to second and third pharyngeal pouches. Gives rise to neurons of unknown fate.
Primordium of the spleen, which goes on to form the spleen proper, while the right splenic promordium degenerates.
Transient splenic primordia that degenerates by NF stage 40.
Internal lymphoid organ derived from left spleen primordia beginning at NF stage 48.
Transient developmental organ which gives rise to oviducts in female (documented to persist in some male frogs).
Structure that is equivalent to the convoluted proximal tubule of metanephric nephrons.
Structure that is the mesonephros nephron's equivalent to the straight proximal segment of a metanephric nephron.
The mesonephric equivalent of the ascending limb, or straight distal segment, of metanephric nephrons.
The site of bicarbonate resorption in the adult kidney. It is equivalent to the convoluted distal segment of metanephric nephrons.
The fused aspects of ventral mesoderm, which have migrated from either side of the prechordal plate, and fused ventrally, just behind the cement gland. They will give rise to the endocardium at NF stage 27&28.
The outlet of the embryonic heart; lies in the floor of the pharynx and conducts blood from the bulbus arteriosis to the aortic arches(1-6).
One of a series of six paired embryological vascular structures which give rise to several major arteries.
The anterior member of a series of six paired arterial connections between the dorsal and ventral aortae. Aortic arch 1 that is part of mandibular arch.
The second in a series paired arterial connections between the dorsal and ventral aortae. Aortic arch 2 that is part of hyoid arch.
The third in a series paired arterial connections between the dorsal and ventral aortae. Aortic arch 3 lies within the 3rd branchial arch and branches directly from the ventral aorta to the lateral dorsal aorta, and are retained as the branchial arteries providing circulation through the gills in the adult.
The artery which arises from aortic arch 1 at NF stage 45 and delivers blood to the filter apparatus. It is visible as a bilateral pair of vessels on the ventral surface of the head, running between the heart and the tip of the jaw.
The aorta of a postembryonic, hatched or immature tadpole, prior to metamorphosis.
The fifth in a series paired arterial connections between the dorsal and ventral aortae. Aortic arch 5 artery is paired and has a common trunk with aortic arch 6 from the ventral aorta, and drains via a separate branch of the lateral dorsal aorta. Aortic arches 5 and 6 supply the trunk and tail with oxygenated blood.
The sixth in a series paired arterial connections between the dorsal and ventral aortae. Aortic arch 6 artery is paired and has a common trunk with aortic arch 5 from the ventral aorta, and drains via a separate branch of the lateral dorsal aorta. It forms part of the pulmonary arteries, and in the later embryo, the ductus arteriosis. Aortic arches 5 and 6 together supply the trunk and tail with oxygenated blood.
One of three branches of the internal carotid artery, the palatine artery supplies the mouth region.
The forth in a series paired arterial connections between the dorsal and ventral aortae, lies within the 4th branchial arch. The paired aortic arch 4 arteries branch directly from the ventral aorta to the lateral dorsal aorta, and are retained as the branchial arteries providing circulation through the gills in the adult.
The endothelium is the thin layer of cells that lines the interior surface of blood vessels, forming an interface between circulating blood in the lumen and the rest of the vessel wall.
The blood vessel that bifurcates from the aorta, and supplies the adbominal and pelvic regions.
Artery consisting of many branches which supply blood to various organs in the viscus. One of the major blood vessels, branching off the dorsal aorta and supplying the embryonic foregut organs- liver, stomach, intestine, spleen and pancreas.
The posterior extension of the dorsal aorta to the tail region, which degenerates at metamorphosis.
The artery that branches from the either side of the dorsal aorta and delivers blood to the musculature of the shoulder region.
One of the major arteries of the head, it is the as the cranial continuation of the aortic arches and the dorsal aorta. It curves ventrally before resuming a dorsal course as it enters the head proper, and it lies ventral to the internal jugular vein. The internal carotid artery gives off palatine, ophthalmic, and cerebral branches by stage NF stage 41.
The anterior continuation of the internal carotid artery, which gives off nasociliary artery anterior to the eye.
A branch of the internal carotid artery that delivers blood to the eye. Together with the opthalmic vein, form a double ring encircling the eye and retina. It enters the eye obliquely by crossing over the ophthalmic vein and the internal jugular vein.
The artery that supplies the network of blood vessels (the mesentry) to the large intestine.
Lymph hearts are pulsatile organs, present in lower vertebrates, that function to propel lymph into the venous system. Two bilaterally symmetrical lymph hearts can be seen adjacent to the somites 3 and 4 by NF stage 40, and can be seen beating by NF stage 43.
Bilaterally paired longitudinal vein; the anterior cardinal returns blood from the head, and the posterior cardinal returns it from the trunk; these two vessels join together on each side as the common cardinal vein, also known as the duct of Cuvier that leads to the heart's sinus venosus.
A vessel that contains or conveys lymph.
The smallest of the blood vessels, parts of the microcirculation, of the liver.
Ventrolateral component of the external jugular vein.
One of the bilateral pairs of vessels are clearly seen on the ventral surface of the head, running between the heart and the tip of the jaw, and drains the filter apparatus. This vein is more developed by NF stage 45, when it crosses the head dorsolaterally to drain into the Duct of Cuvier and pronephric sinus.
The main dorsal head vein, it drains into the Duct of Cuvier, and collects blood from the dorsal jaw region, cerebral veins, the ophthalmic vein and the short pharyngeal vein. It forms loop around the olfactory bulb by NF stage 43.
The anterior cardinal vein returns blood from the dorsal head and drains into the duct of Cuvier via the pronephric sinus.
The pronephric sinsus drains into the heart via the Duct of Cuvier at stage 33&34. It is a system of vessels that initially swell from where the anterior and posterior cardinal veins meet before draining into the Duct of Cuvier ( the common cardinal vein), and then continue to narrow and fold into an characteristic 'S-shape' by NF stage 37&38. It continues to loop on itself, at first a loose, then a dense knot of many vessels by NF stage 45.
Vein that carries blood away from the liver.
One of the veins of the alimentary system. The subintestinal vein is on the right side of the gut and drains the gastric vein on its right side by NF stage 43. The gastric veins carry blood low in oxygen from the surface of the stomach, draining into the left omphalomesenteric vein.
Vein in the tail returning blood from the trunk and tail to the heart, leads directly into the posterior cardinal vein in the posterior trunk.
Any of the veins which collect blood from the lungs and some small vesicles received from the esophagus.
Transient occipital somite that exists from NF stages 17 to 26 only.
Somitic compartment that is a precursor of the axial skeleton.
Transient occipital somite that exists from NF stages 18 to 29 only.
Transient occipital somite that exists from NF stages 18 to 29/30 only.
Transient occipital somite that exists from NF stages 19 to late 30's.
Trunk somite that is initially the 5th somite, first forming around NF stage 19 and becoming more anteriorly positioned as the head somites degenerate. It is the most anterior somite by NF stage 45 and is adjacent to the otic vesicle.
Trunk somite that is initially the sixth somite.
Trunk somite that forms at NF stage 28, by which time head somite 1 has degenerated.
Cranial nerve that supplies the nasal organ.
Any of the major nerves of the head or cephalic region. Twelve pairs of cranial nerves exit/enter the cranium through openings in the skull. The nerves contain efferent axons with motor and glandular functions, as well as afferent axons from cranial ganglia with sensory functions. The nerves are numbered in a rostral to caudal sequence, with the exception of the lateral line nerves.
A depression in the roof of the developing mouth in front of the buccopharyngeal membrane. It gives rise to the anterior pituitary (adenohypophysis), a part of the endocrine system.
Xenopus tadpoles are suspension feeders, and the filter apparatus enables them to trap food particles. In Xenopus the palatoquadrate, ceratohyal and the connecting muscles are responsible for the irrigation and ventilation of the filter apparatus.
Thickened placodal areas located anterior and posterior to the otic vesicle. In Xenopus, there are 5 distinct lateral line placodes, each gives rise to a single lateral line nerve that will innervate lateral line hair cells and convey information on motion to the adjacent hindbrain.
The movable, muscular organ on the floor of the mouth.
The most anterior, or first, pharygeal/branchial arch, composed of the mandibular process, forming the posterior border of the stomodeum, and the maxillary process anterior to the stomodeum, contains the first aortic arch.
A swelling from the 3rd visceral arch at NF stage 35&36, which co-occurs with a depression between the 3rd and 6th, forming the external gills by NF stage 39.
The second pharyngeal/branchial arch; arises as a thickening of the pharygeal wall between the first and second branchial clefts; contains the second aortic arch; forms part of the hyoid bone, tongue and facial musculature.
The third in a series of paired bars in the wall of the pharynx, within which are formed the third aortic arch and the cartilage bar of the visceral skeleton, forms and supports the gills.
Anatomical structure which includes small, calcitonin producing glands originating as epithelial growths from the sixth pharyngeal pouch.
The forth in a series of paired bars in the wall of the pharynx, within which are formed the forth aortic arch and the cartilage bar of the visceral skeleton, forms and supports the gills.
The functional units of the liver including the lobules.
Hollow tree organ, the organ parts of which consist of the bile ducts.
Sphincter muscle that is part of the pyloric region of the stomach.
The dorsal most of the sensory system on the surface of the tadpole consisting of small sensory patches (neuromasts) distributed in discrete lines over the body surface. The lateral line system is stimulated by local water displacements and vibrations, and detects propulsion of the tadpole through the water, as well as facilitating schooling, prey capture, and predator and obstacle avoidance.
Cranial nerve of the caudal lateral line enters the brain between cranial nerves VIII and IX; contains afferents and sensory efferents to the posterior lateral line ganglion and middle ganglion. Fibers from the posterior lateral line ganglion innervate the occipital dorsal lateral line and trunk lateral lines.
The pancreatic bud that gives rise to the accessory pancreatic duct.
Any of the large number of glands of the larval skin, particularly common in the fins and adjacent skin of the trunk; also formed in the former frontal gland area on the upper jaw.
Thin membrane enclosing and immediately adjacent to the ovum. Produced in the ovary. A type of colored melanophore (mobile pigment cells of the dermis & epidermis) that contain fat-soluble carotenoids (obtained from the diet) and pteridines (synthesised from the cell) which are stored in pterinosomes. Their color depends on the pattern of carotenoids and pteridines. Xanthophores are rarely found in pre-metamorphic larvae.
A pigment cell derived from the neural crest. The cell contains flat light-reflecting platelets, probably of guanine, in stacks called reflecting platets or iridisomes. The color-generating components produce a silver, gold, or iridescent color.
A break in the continuity of the optic cup where the two sides of the cup meet.
Neural tissue comprising the proximal part of either of the optic vesicles as they project towards the sides of the head; it remains narrow and constitutes the optic stalk (the peripheral part of each expands to form a hollow bulb).
The most anterior of 5 distinct and partially overlapping functional domains of the premigratory neural crest. CNC cells migrate in four highly conserved streams: mandibular crest, hyoid crest and the anterior and posterior branchial crest.
A pair of lateral diverticula just over the liver rudiment representing the primordia of the lungs, formed by the floor of the foregut just anterior to the liver diverticulum.
Anatomical system that has as its parts the blood and lymph vessels.
Any of the vessels through which blood circulates in the body.
The facial muscles are a group of striated muscles innervated by the facial nerves.
A pigment cell that contains melanin, a brownish-black pigment.
An outgrowth of the cloaca that links the pronephric kidney to the exterior.
The myoblast that forms the muscles of the anterior abdominal walls.
Portion of tissue that consists of mesodermally derived cells and intercellular matrix comprised of protein fibers and carbohydrates, which supports, ensheathes and binds together other tissues.
The protrusion of mesenchymal tissue of the anterior cardinal vein which form lymph sacs.
Inward fold on the surface of the embryonic ectoderm that develops into part of the anal passage.
Notochordal sheath or membrane. Its first indication is at NF stage 24, and it is a distinct membrane by NF stage 28.
Organ that serves as a transient kidney, providing osmoregulation during early developmental stages and then degenerating during metamorphosis.
Material anatomical entity that has inherent 3D shape and is generated by coordinated expression of the organism's own genome.
Anatomical structure consisting of at least two non-overlapping organs, multi-tissue aggregates or portion of tissues or cells of different types that does not constitute an organism, organ, multi-tissue aggregate, or portion of tissue.
Anatomical group that has as its parts distinct anatomical structures interconnected by anatomical structures at a lower level of granularity.
Annotation of data with this anatomy term indicates that a structure or tissue was not specified by the investigator.
Anatomical structure that is an individual member of Xenopus laevis.
Gonochoristic organism that can produce female gametes.
Gonochoristic organism that can produce male gametes.
An experimentally manipulated tissue, or portion of the developing embryo, that can be culture alone, in vitro.
Ectoderm section that has been dissected from the embryo, and treated with activin, and maintained in vitro.
disaggregated/reaggregated ectoderm treated with activin
The main artery of the circulatory system which carries oxygenated blood from the heart to all the arteries of the body except those of the lungs.
A layer of cells produced during the process of gastrulation during the early development of the embryo, which is distinct from other such layers of cells, as an early step of cell differentiation. The types of germ layers are the endoderm, ectoderm, and mesoderm.
Anatomical structure that has as its parts a maximally connected cell compartment surrounded by a plasma membrane.
Anatomical structure that is a primary subdivision of the whole organism.
Cell type that contains a deposition of coloring matter, the first of which differentiate during late tailbud stage, and that by NF stage 56 has produced a fully differentiated larval pigmentation pattern.
Embryonic (precursor) cell of the myogenic lineage that develops from the mesoderm.
Undifferentiated cell that is produced by early cleavages of the fertilized egg (zygote).
A connective tissue cell that secretes an extracellular matrix rich in collagen and other macromolecules.
Type of neuron that is a primary mechanosensory cell, with peripheral neurites innervating the skin with free nerve endings. It first appears in trunk levels at NF stage 33/34, and at NF stage 35/36 has somas that are the largest in the spinal cord. It forms a nearly continuous double row of cells along the cord's medial dorsal surface and contributes ascending and descending axons to the dorsal tract. It appears well back in the tail by NF stage 39, begins to decline at NF stage 50 and is few in number, with pycnotic nuclei, at NF stage 55.
Cell that is the basic unit of nervous tissue, each consisting of a body, an axon, and dendrites, and the purpose of which is to receive, conduct, and transmit impulses in the nervous system.
Organism subdivision that is the part of the body consisting of the cranial and pharyngeal regions.
Organism subdivision that is the part of the body posterior to the head and anterior to the tail.
Organism subdivision that is the terminal, flexible posterior appendage of the larva. It is resorbed during metamorphosis beginning with degeneration of the notochord's distal tip at NF stage 61, followed by degeneration gradually extending to its more proximal regions and reaching its proximal end by NF stage 62. By NF stage 66 it exists only as a small dorsal swelling.
Organism subdivision that has as its parts the jointed appendages used for locomotion and manipulation.
Organism subdivision that is the collection of anatomical structures on the body surface.
Cavity in which food is initially ingested and generally contains teeth, tongue and glands.
One of the pair of limbs that are situated anteriorly, develop in sacs that separate them from the gill chamber, are well-defined buds by NF stage 48, are innervated by NF stage 51, and are ossified by NF stage 59.
One of the pair of limbs that are situated posteriorly, are evident as buds laterally by NF stage 47, and are innervated by NF stage 51.
One of several most distal parts of a limb.
Surface structure that provides one of the small external openings of the head that give passage to air for breathing.
An internal organ of the body; especially: one (as the heart, liver, or intestine) located in the great cavity of the trunk proper.
A digit that is one of several most distal parts of a hind limb.
A digit that is one of several most distal parts of a forelimb.
Anatomical structure that has as its parts two or more portions of tissue of at least two different types and which through specific morphogenetic processes forms a single distinct structural unit demarcated by bona-fide boundaries from other distinct structural units of different types.
Multi-tissue structure that is not part of a compound organ.
Multi-tissue structure that is part of a compound organ.
Anatomical structure that consists of similar cells and intercellular matrix, aggregated according to genetically determined spatial relationships.
Anatomical structure that has as its parts two or more multi-tissue structures of at least two different types and which through specific morphogenetic processes forms a single distinct structural unit demarcated by bona fide boundaries from other distinct anatomical structures of different types.
An anatomical structure that exists only before the organism is fully formed.
An embryonic structure that is the rudiment or commencement of a part or organ.
Primary germ layer that can give rise to both mesoderm and endoderm.
Portion of tissue that consists of one or more layers of epithelial cells connected to each other by cell junctions and that is underlain by a basal lamina.
Portion of tissue consisting of loosely organized undifferentiated mesodermal cells that give rise to such structures as connective tissues, blood, lymphatics, bone, and cartilage.
Portion of tissue that consists of a fasciculated group of axons.
A mature female germ cell that is capable of initiating formation of a new individual by fusion with a male gamete.
Connective tissue in which fat is stored.
Anatomical structure associated with the gonads which vary in form among amphibians but are primarily composed of adipose tissue and are thought to be a source of nutrients for the gonads. A body of adipose tissue, in the form of finger-like projections, usually associated with the anterior end of the testis and ovaries. Fat bodies are suspended from the body wall by dorsal mesentry which is fused with the gonadal mesentry (the mesovarium or mesorchidium).
Region located near the pronephros and pronephric ducts that is a site of hematopoiesis in the embryo.
A rectangle of dorsal mesendoderm and ectoderm from an early-gastrula-stage Xenopus laevis embryo. It is approximately 60 deg to 90 deg wide, extending from the bottle cells to the animal pole.
A relatively undifferentiated cell that retains the ability to divide and proliferate throughout life to provide progenitor cells that can differentiate into specialized cells.
A stem cell from which all cells of the lymphoid and myeloid lineages develop, including blood cells and cells of the immune system.
Spatial concept denoting the front surface of the body; often used to indicate the position of one structure relative to another.
Spatial concept denoting the back surface of the body.
Structure consisting of a cartilaginous skull that begins to form during early tadpole stage.
Anatomical system that provides physical support to the organism.
Skeletal structure of the paired, anterior appendages.
Skeletal structure of the paired, posterior appendages.
Arched skeletal structure that supports the forelimbs, the rudiments of which can be distinguished in mesenchyme at NF stage 51, and is complete by NF stage 60.
Arched skeletal structure that supports the hind limbs, begins to develop at NF stage 50, and is ossified by NF stage 66.
The anterior limb bud which develops into the fore limb; oval shaped in dorsal aspect by NF stage 50, and paddle shaped by NF stage 53; all four fingers and melanophores apparent by NF stage 54.
The bilateral thickening of the ectoderm in the region of the first noticeable at NF stage 47, and innervated by NF stage 51. The hind limb buds develop before the forelimb buds.
Skeletal structure that has as its parts the vertebral column, located in the dorsal part of the trunk, and formed by a series of vertebrae. It provides suspension for the appendicular skeleton and protection for the spinal nerve cord.
Skeletal system that is part of the head, including the splanchnocranium, chondrocranium, and dermatocranium.
The single vertebra that is immediately posterior to the skull, specifically the atlas, and lacks ribs.
The bones that make up the tail region of the tadpole.
Rodlike caudal bony structure unique to anurans that lies within a compartment formed by the elongated, anteriorly oriented pelvic girdle. The urostyle is formed by the fusion of the coccyx and the hypochord.
Anatomical structure consisting of a narrowly triangular chamber supported by a series of semicircular cartilages in which part of the sound-production system is located.
Skeleton encasing the brain and auditory apparatus.
Paired cartilaginous component of the lower jaw that fuses together through a median inferior labial cartilage, resulting in a single curved bar of cartilage by metamorphic climax. During metamorphosis it is surrounded by the developing dentale and goniale.
Any of the coiled tubules located in the testes in which spermatozoa are produced.
Any of the major paired nerves of the head region, which exit and enter the cranium through openings in the skull.
Cranial nerve that runs to the eye muscles.
Cranial nerve, also known as the pathetic nerve, that runs to the eye muscles.
Cranial nerve that branches into the ophthalmic (supplying the skin of the nose and upper jaw) and the mandibular (supplying the lower jaw).
Cranial nerve, also known as the abducent nerve, that runs to the eye muscles.
Cranial nerve that branches into the supraorbital (supplying the skin of the eye region and the lateral line organs here), the palatine (to the roof of the buccal cavity), and the hyomandibular (dividing into the jugular and mental branches).
Cranial nerve that branches into the ramus communicans (to the skin), the pretrematic (to the walls of the pharynx and mouth, viscero-sensory fibers), and the larval post-trematic branch (lost in the adult).
Cranial nerve that branches into the lateral (to body sense organs) and the intestino-accessorial (to the skin, muscles of shoulder, hyoid, larynx, gut, lungs, and heart).
A dorsally projecting part of the brain concerned especially with the coordination of muscles and the maintenance of bodily equilibrium, situated between the brain stem and the back of the cerebrum.
Irregularly shaped cavity in the rhombencephalon, between the medulla oblongata, the pons, and the isthmus in front, and the cerebellum behind. It is continuous with the central canal of the cord below and with the cerebral aqueduct above, and through its lateral and median apertures it communicates with the subarachnoid space.
Posterior portion of the hindbrain which controls respiration, heartbeat, digestion, and swallowing as well as some locomotor responses.
Any of the projections on each side of the vertebra from the point where the neural arch lamina joins the pedicel for the articulation with the head of a single-headed rib or the upper head of a double-headed rib. Also called diapophyses. They provide surfaces for the attachment of muscles. In anurans, the term transverse process is used in reference to the processes associated with the presacral and postsacral vertebrae.
Anatomical structure consisting of a small, pointed keratinized appendage at the end of each of the three inner toes of the hind limbs.
The principal auditory organ of frog that utilizes both mechanical and electrical (hair cell-based) frequency tuning mechanisms for hearing, located near the junction of the utricle and the saccule bones of the inner ear.
A sensory structure in the lagenar portion of an amphibian's membranous labyrinth between the oval and round windows.
Anatomical structure which produces gametes as well as certain sex hormones controlled by the pituitary gonadotropins. Reproductive organ that produces and releases eggs (ovary) or sperm (testis).
A mature male germ cell that develops from a spermatid.
A cell that is within the developmental lineage of gametes and is able to pass along its genetic material to offspring.
Primitive cell type that is involved in the reproduction of the organism beginning with the sexual differentiation of the gonads at NF stage 52. In males specifically, it migrates from the genital ridge cortical region into the medullary tissue, where it forms spermatogonia. In females it is embedded in the cortical region and multiplies as oogonia.
Anatomical system that protects the body from foreign substances, cells, and tissues by producing the immune response and that includes especially the thymus, spleen, lymphoid tissue, lymphocytes including the B cells and T cells, and antibodies.
The immune system of a postembryonic, hatched or immature tadpole, prior to metamorphosis.
The complete system of biological structures and processes within the adult organism that protects against disease by identifying and killing pathogens and tumor cells.
A cell of the B cell, T cell, or natural killer cell lineage.
A lymphocyte that can spontaneously kill a variety of target cells without prior antigenic activation via germline encoded activation receptors and also regulate immune responses via cytokine release and direct contact with other cells.
One of the two types of lymphocytes (the others being T cells). All lymphocytes begin their development in the bone marrow. B cells are involved in so-called humoral immunity.
An immature T cell located in the thymus.
Anatomical group that has its parts adjacent to one another.
Structure that is an early outgrowth of a presumptive limb.
Anatomical structure that consists of cell parts and cell substances and together does not constitute a cell or a tissue.
Acellular anatomical structure that consists of a thin sheet of fibrous proteins that underlie and support the cells of an epithelium. It separates the cells of an epithelium from any underlying tissue.
Compound organ that does not contain macroscopic anatomical spaces.
Compound organ that contains one or more macroscopic anatomical spaces.
Skeletal structure that has as its parts the pectoral and pelvic girdles, which articulate with the axial skeleton, together with their associated limbs, the forelimbs and hind limbs.
Cranium which consists of dermally derived bones.
An anatomical cluster that is part of the cranium and structurally supports the eye.
Anatomical cluster that is located in the anterior region of the neurocranium and provides structural support for the olfactory organs.
An anatomical cluster that is located in the posterior region of the neurocranium and forms the margin of the foramen margin and occipital condyles.
Anatomical cluster that forms the floor and side walls of the middle part of the cranium.
Anatomical cluster that is a posterolateral part of the neurocranium and structurally supports the vestibuloauditory system.
Regional skeletal system of the jaws, hyoid and branchial arches.
Skeletal and cartilaginous elements of the branchial arches; the last five of the set of seven pharyngeal arches; the numbering system can be confusing; generally branchial arch #1 is the first branchial arch, or the third pharyngeal arch, but some authors do not follow this convention.
Skeletal and cartilaginous elements of the first branchial or pharyngeal arch.
Skeletal and cartilaginous elements of the second branchial or pharyngeal arch.
Skeletal and cartilaginous elements of the third branchial or pharyngeal arch.
Skeletal and cartilaginous elements of the forth branchial or pharyngeal arch.
Any spatial descriptor that describes the orientation of the anatomical features of an embryo.
A region of the whole organism that contains a recognizable set of structures or anatomical entities.
Spatial concept pertaining to being toward the middle or inside.
Spatial concept denoting a part of the body that is closer to the center of the body than another part.
Spatial concept denoting a part of the body that is farther away from the center of the body than another part.
Non-material anatomical entity of three dimensions, that is generated by morphogenetic or other physiologic processes; is surrounded by one or more anatomical structures; contains one or more organism substances or anatomical structures.
Cardiac chamber which consists of a wall that surrounds the cavity of a ventricle. The amphibian heart has a single ventricle and an outflow tract with an incomplete spiral septa.
A part of the nervous system responsible for processing sensory information.
The sensory system used for balance and hearing.
The sensory system used for olfaction (the sense of smell).
The sensory system used for the sense of taste.
Part of the circulatory system which consists of a series of vessels which collect blood (exclusive of erythrocytes) which seep through capillary walls and return it to the veins. The lymphatic system of vasculature drains lymph fluid from the tissue spaces of most organs and returns it to the blood vasculature for recirculation. The lymphatic sytem functions in immune responses. Anurans generate a lot lymphatic fluid, largely as a consequence of their very `leaky' vasculature and high interstitial compliance. Lymph is ultimately pumped into the venous system by paired, dorsally located lymph hearts. Hedrick et al (2007) show that lung inflation and deflation assists lymph movement. Lymph is moved during lung deflation to the subvertebral sac from anterior and posterior lymph sacs. During lung inflation, increased lymph sac pressure moves lymph to axillary regions, where lymph hearts can return lymph to the vascular space. (see Hedrick et al 2007).
Epithelium that is part of a developing tooth or dental organ.
Hollow epithelial tube on dorsal side of the embryo that develops into the central nervous system.
Polymorphic cell type that forms cartilage.
Cell type that is a component of the glomus.
The cluster of bones in the wrist between the radius, ulna and metacarpus, they do not belong to individual finger, but allow the wrist to move and rotate.
Either of the paired, long bones of endochondral origin formed by the fusion of the radius and ulna.
Either of the paired, elongate, cylindrical bones of endochondral origin that extend from the pectoral girdle to the elbows. The humerus is the long bone in the forelimb that runs from the shoulder to the elbow.
A bone of the wrist of the hindlimb, which remains cartilaginous until NF stage 66.
Bone of the lower hind leg, which undergoes ossification from NF stage 56 to stage 66.
Either of the paired, elongate, cylindrical bones of endochondral origin that form the thighs, extending from the pelvic girdles to the knees. Proximal bone of the hind leg, which begins to ossify at NF stage 55.
The layer within the retina where the photoreceptor cell receptor segments reside.
The monolayer of pigmented epithelium covering the neural retina.
The brain structure where the two separate inputs from the two eyes are combined into a single, integrated map.
Anatomical cavity bounded by the derivatives of the branchial arches.
Trunk muscles that lies dorsal to the horizontal septum.
A cell that takes up stuff and metabolizes it.
Any of the cell types of the digestive system that secrete amino acid peptides or polypeptides.
Exocrine functioning cells of the pancreas.
A cell that secretes alkaline substances.
A cell whose primary function is to prevent the transport of stuff across compartments.
A surface epithelial cell of stratified squamous epithelium of cornea, tongue, oral cavity, esophagus or cloaca.
A cell of ectomesenchymal origin concerned with the formation of the layer of cementum on the roots of teeth.
A chondroblast is a cell which originates from a mesenchymal stem cell and forms chondrocytes, commonly known as cartilage cells.
A cell which moves among different tissues of the body, via blood, lymph, or other medium.
A cell of the early embryo at the developmental stage in which the blastomeres, resulting from repeated mitotic divisions of the fertilized ovum (zygote), form a compact cell mass.
An undifferentiated cell produced by early cleavages of the fertilized egg (zygote).
A cell of the embryo in the early stage following the blastula, characterized by morphogenetic cell movements, cell differentiation, and the formation of the three germ layers.
A cell of the outer of the three germ layers of the embryo.
A cell whose function is determined by the generation or the reception of an electric signal.
A cell of an endocrine gland, ductless glands that secrete substances which are released directly into the circulation and which influence metabolism and other body functions.
A cell of the inner of the three germ layers of the embryo.
A cell that is usually found in a two-dimensional sheet with a free surface.
A cell of an exocrine gland, i.e. a gland that discharges its secretion via a duct.
Individual secretory cells of the hatching gland that secrete an enzyme that dissolves or weakens the egg jelly and facilitates hatching.
A modified epidermal cell located in the stratum basale. They are found mostly in areas where sensory perception is acute.
A cell of the middle germ layer of the embryo.
A non-sensory cell surrounding the neuromast support cells and neuromast hair cells, separating the neuromast from the epidermis, and secreting cupula in which the ciliary bundles of all the hair cells are embedded.
A non-sensory cell of the neuromast that extends between the sensory hair cells from the basement membrane to the apical surface; neuromast support cells are surrounded by neuromast mantle cells.
A non-ciliated columnar cell that extends from the epithelial free margin to the basement membrane of the olfactory epithelium.
A slender, contractile, mesenchymal-like cell found in close association with capillary walls. They are relatively undifferentiated and may become fibroblasts, macrophages, or smooth muscle cells.
A stem cell that can give rise to cell types of the body other than those of the germ-line.
Either of the pair of structures lying on either side of the dorsal aorta in which fluid balance is regulated and waste is excreted out in the form of urine.
Presumptive precardiac cells which lie as paired primordia 30 to 45° on either side of the dorsal midline of the Xenopus embryo, and as gastrulation proceeds, these migrate laterally, eventually fusing at the anterior ventral midline, where they differentiate into cardiac tissue. Cells that give rise to the linear heart tube of the fused heart primordium and derive from the cardiac crescent.
A tube shaped portion of tissue lined with epithelial cells that collects secretions and routes them to their destination.
Epithelium that consists of more than one layer of epithelial cells.
Epithelium that consists of a single layer of epithelial cells.
Unilaminar epithelium that consists of a single layer of columnar cells.
Unilaminar epithelium that consists of a single layer of cuboidal cells.
Unilaminar epithelium that consists of a single layer of squamous cells.
Anatomical cluster of the central body axis including the cranium, vertebrae, notochord, ribs, and sternum.
Organ entity that may have different tissue compositions at different stages and typically involved in mechanical support.
Skeletal element that is composed of cartilage tissue and may be permanent or transient.
Skeletal element that forms superficially in the organism, usually in association with the ectoderm.
Skeletal element that forms as a replacement or substitution of another element or tissue.
A skeletal element that has the potential to participate in endochondral ossification, and may participate in intramembranous ossification.
Replacement bone that forms within cartilage.
Main component of the vertebral column. It consists of two essential parts, a dorsal neural arch and a ventral centrum.
Anatomical structure that is a natural outgrowth, projection, or appendage. A process can be part of a bone, cartilage, tissue, fin, scale, etc.
Anatomical structure that is an aggregation of similar cells from which cartilages and bones form, and from which chondrogenesis and osteogenesis are initiated during repair and/or regeneration. (Hall and Miyake 1995).
Cell condensation that is an aggregation of mesenchymal cells that are committed to differentiate into chondroblasts and chondrocytes.
Cranial skeleton derived from neural crest cells.
Skeletal system that undergoes direct development and includes elements that either develop in association with the basement membrane of the ectoderm or are homologous with such elements; includes dermatocranium, components of the appendicular skeleton, teeth and tooth-like elements of the oropharynx, and integumentary elements.
Skeletal system that undergoes indirect development and includes elements that develop as a replacement or substitution of other elements or tissues.
Combination of protein fibers, ground substance and tissue fluid; typically has embedded cells.
Cartilage tissue intermediate between hyaline cartilage and dense connective tissue; contains of abundant collagen fibers; chondrocytes often arranged in columns.
Cartilage tissue primarily composed of type II collagen (thin fibrils) and a glassy appearance.
Connective tissue that is dominated by collagen fibres organized into a definitive pattern (e.g., parallel to one another), with comparatively fewer cells (mostly fibroblasts).
Dense regular connective tissue connecting two or more adjacent skeletal elements or supporting an organ.
A layer consisting mainly of proteins (especially collagen) and glycosaminoglycans (mostly as proteoglycans) that forms a sheet underlying or overlying cells such as endothelial and epithelial cells. The proteins are secreted by cells in the vicinity.
Proteinaceous extracellular matrix that is avascular and consists primarily of glycosaminoglycans.
Extracellular matrix that is mineralized.
Bone tissue that is an unmineralized bone matrix deposited by osteoblasts prior to the mineralization of bone tissue.
Avascular GAG-rich matrix that is mineralized.
non-mineralized avascular GAG-rich matrix
Avascular GAG-rich matrix that is not mineralized.
Connective tissue that functions in mechanical and structural support.
Bone tissue mineralized with hydroxyapatite.
Hyaline cartilage tissue that is mineralized.
Cartilage tissue that is not mineralized.
non-mineralized hyaline cartilage tissue
Hyaline cartilage tissue that is not mineralized.
Cell condensation that is a well-defined population of densely organized mesenchymal cells that aggregates adjacent to an epithelium.
Skeletal tissue that is part of the exoskeleton and derived from an odontogenic papilla.
Odontogenic papilla located along the jaws or pharyngeal skeleton.
Fibrous connective tissue that surrounds cartilage.
Fibrous connective tissue that surrounds the notochord; includes a layer of elastin.
Collagen-rich odontogenic tissue characteristic of teeth and tooth-like skeletal elements (e.g., odontodes); mature dentine is mineralized and develops from predentine tissue; often (but not always) tubular and acellular.
Odontogenic tissue that is collagen-rich and characteristic of vertebrate teeth and tooth-like structures (e.g., odontodes) deposited by preodontoblasts and odontoblasts that are typically excluded from the matrix.
Connective tissue that is matrix-poor with large number of vacuolated cells.
Nerve that is a branch of cranial nerve VIII and innervates the cristae ampullaris.
A portion of tissue that is re-growing after damage or amputation.
A regenerating tissue composed of a proliferative mass of undifferentiated progenitor cells from which new differentiated structures arise.
The unsupported flaps of epidermis-covered, loose connective tissue extending the length of the dorsal tail muscle, originating at or near the tail-body junction, and extending posteriorly to slightly beyond the tip of the notochord and tail musculature.
Multi-tissue structure which is part of the diencephalon ventral to the thalamus consisting of connecting fibers and is a center for control of the autonomous nervous system.
Decussation of cranial nerve II axons whereby some cross the midline and some remain ipsilateral.
Diencephalic nucleus that is part of the preoptic area and is ventrolateral to the caudal parvocellular preoptic nucleus.
Any of the 5 sequential sections of developing hindbrain, all are posterior to the midbrain-hindbrain boundary.
The 2nd, most anterior segment of the developing hindbrain, and along with r3, is dorsal to brancial arch 1.
The 3rd segment of the developing hindbrain, between r2 and r4 rhombomeres, and along with r2, is dorsal to branchial arch 1.
The 4th segment of the developing hindbrain, between r3 and r5 rhomomeres and dorsal to branchial arch 2.
The 5th segment of the developing hindbrain, bewteen r4 and r6, and dorsal to branchial arch 3.
The 6th and most posterior segment of the developing hindbrain, directly bordering the midbrain-hindbrain boundary, and dorsal to branchial arch 4.
Specialized epithelial cells involved in the maintenance of osmotic homeostasis. They are characterized by abundant mitochondria and ion transporters.
One of the two edges of the neural groove.
Portion of tissue that is part of the anterior neural plate and will form the optic vesicle.
The field of naive ectoderm at the anterior of the neural stage embryo. It is positioned at the border between the future epidermis and the anterior neural plate/neural crest forming regions and is subdivided into 2 distinct domains: the anterior placodal region which is anterior to the neural plate, and the posterior placodal area which is lateral to the neural crest.
An embryonic structure positioned halfway between the prospective eye and ear, adjacent to the future midbrain-hindbrain boundary. The profundal and the trigeminal ganglia are separate distally but fused at their proximal end as they condense around NF stage 24.
Epithelium which borders the anterior and equitorial region of the lens. Lens growth occurs via the differentiation of additional fibre cells from lens epithelial cells.
Portion of tissue comprising fibers that form the bulk of the lens. They are long, thin, transparent cells.
A neuron that laterally connects other neurons in the inner nuclear layer of the retina.
A type of interneuron that has two neurites, usually an axon and a dendrite, extending from opposite poles of an ovoid cell body.
Interneuron of the retina. They integrate, modulate, and interpose a temporal domain in the visual message presented to the retinal ganglion cells, with which they synapse in the inner plexiform layer. They lack large axons.
Type of neuron that receives neural inputs via bipolar, horizontal and amacrine cells. The axons of these cells make up the optic nerve.
Diencephalic white matter (tract) which is comprised of retinal ganglion cell axons after which they have passed through the optic chiasm.
The boundary between non-neural ectoderm and the neural plate of neural stage embryos, and give rise to the neural crest and cranial placodes.
Any of bilaterally paired tubes connecting the pronephric glomeruli to the pronephric ducts.
A portion of forelimb tissue that is re-growing after damage or amputation.
A portion of hind limb tissue that is re-growing after damage or amputation.
A portion of tail tissue that is re-growing after damage or amputation.
A portion of eye tissue that is re-growing after damage or amputation.
One of the two photoreceptor cell types in the retina. In cones the photopigment is in invaginations of the cell membrane of the outer segment. Cones are less sensitive to light than rods, but they provide vision with higher spatial and temporal acuity, and the combination of signals from cones with different pigments allows color vision.
One of the two photoreceptor cell types of the retina. In rods the photopigment is in stacks of membranous disks separate from the outer cell membrane. Rods are more sensitive to light than cones, but rod mediated vision has less spatial and temporal resolution than cone vision.
The developing female gamete of the pre-vitellogenic stage.
The developing female gamete of the early vitellogenic stage.
The developing female gamete of the mid-vitellogenic stage.
The stage in the developing female gamete where polarization along the animal-vegetal axis is established.
A sheet of extracellular matrix that separates the outer myocardial cell layer from the inner endocardial tube in the early embryonic heart. As the heart is going through the looping stages, this extracellular matrix/cardiac jelly starts to thicken in two regions, the atrioventricular canal region and the ventricular outflow tract region. These two discrete swellings of cardiac jelly are known as cardiac cushions. The cardiac jelly plays a central role in the septation of the heart and comprises most of the thickness of the heart wall at early stages, but disappears as the heart differentiates.
The apical ectodermal ridge is a thickened layer of ectodermal cells at the distal tip of a developing limb bud. Along with the zone of polarizing activity, it is a crucial organizing region during limb development.
Anatomical cluster which consists of rapidly dividing cells.
The part of the heart connecting the atrium to the cardiac ventricle.
Endocardium that is part of the atrioventricular canal.
Portion of tissue that prevents regurgitation of blood from the ventricles to the atria or from the pulmonary arteries or aorta to the ventricles.
A mechanoreceptor cell located in the inner ear that is sensitive to auditory stimuli. The accessory sensory structures are arranged so that appropriate stimuli cause movement of the hair-like projections (stereocilia and kinocilia) which relay the information centrally in the nervous system.
A horizontal patch of cristae/sensory epithelia cells of the inner ear.
Presumptive structure at the animal pole of the blastula that will develop into ectoderm.
A posterior patch of cristae/sensory epithelia cells of the inner ear.
Presumptive structure that will develop into paraxial mesoderm.
The interface between the dorsal neuroepithelium and the roof plate of the fourth ventricle. The source of a number of migratory neuron populations of the hindbrain.
Portion of tissue that is a patch of thickened, pseudostratified epithelium in the inner ear, consisting of regular arrays of sensory hair cells interspersed with supporting cells. The macula saccule senses linear acceleration and gravity.
Anterior patch of cristae/sensory epithelia cells of the inner ear.
A specialized epithelial cell involved in sensory perception. Restricted to special sense organs of the olfactory, gustatory, and vestibuloauditory systems; contain sensory cells surrounded by supportive, non-receptive cells.
The portion of the heart through which blood flows into the pulmocutaneous and systemic arteries. In Xenopus the outflow tract is derived from cardiac precusor cells of the secondary heart field, and septation is incomplete.
A portion of either the left ventricle or right ventricle of the heart through which blood passes in order to enter the great arteries. The right ventricular outflow tract (RVOT) is an infundibular extension of the ventricular cavity which connects to the pulmonary artery. The left ventricular outflow tract (LVOT), which connects to the aorta, is nearly indistinguishable from the rest of the ventricle.
The thin, spiral-shaped membranous structure within the ventricular outflow tract of the heart.
Ganglion which provides afferent innervation for hair cells associated with both the auditory and vestibular components of the inner ear. As the otic placode invaginates into a cup neuroblasts delaminate from the anterior ventral aspect of the otic epithelium to give rise to neurons of the vestibulocochlear (statoacoustic) ganglion of cranial nerve VIII.
Any network of intercommunicating blood vessels.
Region that is overlapping, anterior, and dorsal to the main body of the ventral blood island.
A pluripotent cell in the ventral blood island that can give rise to mesenchymal cells including erythrocytes and endothelial cells.
One of two veins that run upward at first in front, and subsequently on either side of the intestinal canal. They unite on the ventral aspect of the canal, and beyond this are connected to one another by two anastomotic branches, one on the dorsal, and the other on the ventral aspect of the duodenal portion of the intestine, which is thus encircled by two venous rings; into the middle or dorsal anastomosis the superior mesenteric vein opens. The portions of the veins above the upper ring become interrupted by the developing liver and broken up by it into a plexus of small capillary-like vessels termed sinusoids.
A cell of the monocyte, granulocyte, mast cell, megakaryocyte, or erythroid lineage.
An endothelial cell comprises the outermost layer or lining of anatomical structures and can be squamous or cuboidal.
A immature or mature cell in the lineage leading to and including erythrocytes.
Posterior vascular precursor cells of the tail region.
Blood vessels of the retina. May be visible in periocular stainings.
Vessels that are associated with the posterior region of the lens.
The hyaloid artery is a branch of the ophthalmic artery, which is itself a branch of the internal carotid artery. It is contained within the optic stalk of the eye and extends from the optic disc through the vitreous humor to the lens. Its purpose is to supply nutrient to the developing lens.
The anterior cerebral veins cross the head dorsally at NF stage 37-38. It drains into the vena capitis medialis.
Vein that drains the dorsal longitudinal vessel and the caudal portions of the venous capillary network of the medulla oblongata. The cerebral veins cross the head dorsally at NF stage 37-38. It drains into the vena capitis lateralis.
The cerebral veins are divisible into external and internal groups according to the outer surfaces or the inner parts of the hemispheres they drain into. The veins are the anterior cerebral veins, posterior cerebral veins, and middle cerebral vein which cross dorsally between the bilateral vena capitis lateralis.
The middle cerebral veins cross the head dorsally at NF stage 37-38. It drains into the vena capitis lateralis.
The pulmonary arteries carry blood from heart to the lungs. They are the only arteries that carry deoxygenated blood. Develops from aortic arch 6 in Xenopus.
A mesenchymal stem cell capable of developing into blood vessel endothelium.
Veins that sprout from the posterior cardinal vein, growing dorsally between the somites, and will join, and drain the dorsal longitudinal anastomosing vessel.
The small branching sprouts of the dorsal aorta that grow across the medial surface of the somite, turn right angles to grow over that surface and then fuse with other sprouts and form the vertebral arteries adjacent to the neural tube; the intersomitic arteries supply the body wall and persist in the adult as the posterior intercostal, subcostal and the lumbar arteries.
In the trunk region, the subintestinal vein drains into the omphalomesenteric veins, which breaks up to merge with the vitelline network at NF stage 40.
The artery that crosses the brain dorsally, and meets the metencephalic vein.
The vein that crosses the brain dorsally, parallel with the mid-cerebral vein, and meets the metencephalic artery.
The dorsal branch/remnant of the vena capitis medialis, that drains blood from the eye. Together with the opthalmic artery, form a double ring encircling the eye and retina.
One of the major dorsal head veins which drains into the anterior cardinal vein, the other being the vena capitas lateralis.
One of the major dorsal head veins which drains into the anterior cardinal vein, the other being the vena capitas medialis.
The subintestinal vein is formed from and drains into the left omphalomesentric vein, and by NF stage 40, it is on the left side of the gut. It moves to the most ventral aspect of the gut during NFstage 41, and is on the right side of the gut by NF stage43.
The major artery of the midbrain, which crosses the midbrain medially to meet it's partner the mesencephalic vein.
The major vein of the midbrain, which crosses the midbrain medially to meet it's partner the mesencephalic artery.
The main artery of the olfactory region which arises from the cerebral artery at NF stage 41.
A plexus of capillaries that is visible anteromedial to the eye. The choroid is the vascular layer of the eye, containing connective tissue, and lying between the retina and the sclera. The choroid provides oxygen and nourishment to the outer layers of the retina. Along with the ciliary body and iris, the choroid forms the uveal tract.
capillary lamina of choroid or choriocapillaris
Intersomitc vessels enter the dlav in a regular pattern at each intersomitic junction. Posterior to the gut, the dlav drains into the fused posterior cardinal vein by a minor right branch and a major left branch. By NF stage 36 the dlav extends fully to the tip of the tail.
dorsal longitudinal anastomosing vessel- left branch
The major (left ) branch of the dorsal longitudinal anastomosing vessel (dlav), remains as the sole branch after the right branch breaks up at stage 44.
dorsal longitudinal anastomosing vessel- right branch
The minor (right) branch of the dorsal longitudinal anastomosing vessel (dlav), the right branch disappears during NF stage 44.
Part of the telencephalon, comprised of paired anterior outgrowths of either of the cerebral hemispheres in which the olfactory nerve exits. In Xenopus,the olfactory bulbs begin to fuse at NF stage 50, fusion is complete around NF stage 58. The cerebral vein loops around the olfactory bulb by NF stage 43.
The cells that comprise cardiac muscle, specificially the myocardium.
The outer membrane/wall of the developing heart, surrounding the myocardium. Peritoneum that surrounds the heart.
Muscle which is paired and runs anterio-posteriorly along the heart and is covered with epicardium.
The field of cardiac progenitor cells that form the heart tube in the embryonic heart.
The population of cells located in the splanchnic mesoderm that contribute to the formation of the spiral septum of the outflow tract of the embryonic heart, it is located anterior to the primary heart field.
The most anterior of the migrating cranial neural crest streams, running along the posterior edge of the eye primordium, below the eye and to the border of the cement gland.
The second most anterior of the migrating cranial neural crests streams.
The discrete swellings of cardiac jelly in the outflow tract and ventricular walls of the developing embryonic heart.
The most anterior of 5 distinct and partially overlapping functional domains of the premigratory neural crest. In Xenopus, CNC cells migrate in four highly conserved streams: mandibular crest, hyoid crest and the anterior and posterior branchial crest.
One of the 5 distinct and partially overlapping functional domains of the premigratory neural crest. The vagal and sacral neural crest cells develop into the ganglia of the enteric nervous system, also known as the parasympathetic ganglia.
Skeletal element that is often isolated, small, and is usually ossified.
Mineralized bone tissue that always includes non-terminally differentiated osteoblasts and osteocytes.
Odontoid tissue that is deposited by cementoblasts onto dentine tissue and functions to attach teeth, odontodes and other odontogenic derivatives to bone tissue and the integument.
Cartilage tissue that is flexible and contains abundant elastic fibers.
Skeletal tissue that consists of an avascular, noncollagenous, hypermineralized matrix that is deposited by ameloblasts that are excluded from the matrix. Enamel develops from organic pre-enamel tissue that is replaced by a largely inorganic matrix.
Skeletal tissue that is hypermineralized and aprismatic and deposited by a combination of ameloblasts and odontoblasts that are excluded from the matrix. Enameloid develops from pre-enameloid tissue.
Skeletal tissue that is avascular tubular mineralized matrix, primarily made of dentine that is deposited by odontoblasts that are excluded from the matrix; develops from pre-dentine tissue.
Odontogenic tissue that is avascular non-mineralized matrix that is deposited by preameloblast and ameloblasts that are excluded from the matrix.
Odontoid tissue that is avascular non-mineralized matrix that is deposited by odontoblasts and ameloblasts that are excluded from the matrix.
Replacement element; an ossicle; often an endochondral replacement element that has cartilage and bone states that develops in dense regular connective tissue (e.g., tendons and ligaments).
A sac-like cavity ventral to the liver, lying in the sub-mesodermal space and closed by a thin sheet of ectodermal cells, from which the future gall bladder develops.
One of the 2 subregions of the pre-placodal ectoderm, which lies abutting and anterior to the neural plate.
One of the 2 subregions of the pre-placodal ectoderm, which lies abutting and lateral to the neural crest.
The small pre-placodal ectoderm area that develops at the midline of the anterior neural ridge, abutting the anterior neural plate, and invagintes to form Rathe's pouch, which in turn forms the anterior lobe of the pituitary gland and gives rise to the endocrine secretory cells of the pituitary.
The region that delineates the rostral boundary of the neural plate in the neural stage embryo, and is devoid of neural crest cells. It gives rise to olfactory placodes, some elements of the forebrain, and the anterior lobe of the pituitary gland.
The region of the diencephalon above Rathke's pouch, and forms the posterior lobe of the pituitary.
The most anterior of the epibranchial placodes, associated with the 1st pharyngeal cleft and it contributes to the distal ganglia of cranial nerve VII (facial nerve).
The central of the three epibranchial placodes, associated with the 2nd pharyngeal cleft and it contributes to the distal ganglia of cranial nerve XI (glossopharyngeal nerve).
The most posterior of the epibranchial placodes, in Xenopus in 3 distinct zones, associated with the 3rd -6th pharyngeal clefts, and contributing to the facial, lateral line and glossopharyngeal ganglion.
A small motor nerve which emerges from the lateral wall of the medulla with the roots of the vagus nerve, and innervates a single pectoral suspensory muscle, the m.cucullaris.
This nerve leads to the muscles of the tongue, and has both sensory and motor functions.
The narrow bridge that links the two glomera of the pronephric kidney.
Nieuwkoop and Faber stage 1; age 0 hr; corresponding to the following external morphological criteria: One cell stage, shortly after fertilization. Pigmentation darker ventrally than dorsally. Length: 1.4 - 1.5 mm.
The stages from Nieuwkoop and Faber stage 22 to stage 28.
The stages from 64-cell embryo to Nieuwkoop and Faber stage 9, during which the solid morula acquires an internal cavity.
The stages from 2-cell to 64-cell embryo, during which the zygote undergoes synchronous divisions into 2, 4, 8, 16, etc. blastomeres.
The stages from Nieuwkoop and Faber stage 10 to stage 12.5, during which gastrulation takes place, with a proportion of cells migrating below the surface of the embryo to form two inner layers (endoderm and mesoderm) and the cells which remain outside spreading over the whole surface of the embryo to form the ectoderm.
The stages from Nieuwkoop and Faber stage 13 to stage 21, during which the future nervous system appears as a thickened plate in dorsal ectoderm, the plate then rolling up at its sides to form a tube.
Any of the developmental stages from Nieuwkoop and Faber stage 20 to stage 44 (feeding), including the beginning of hatching (NF stage 35/36).
The stages from feeding to the end of metamorphosis. Encompasses Weisz's first-form tadpole (equivalent to NF stages 45 to 49), second-form tadpole (NF 49 to 56) and third-form tadpole (NF 56 to 60-plus) stages.
The stage of being a fully formed animal.
The stage of being a sexually immature adult animal.
Nieuwkoop and Faber stage 2; age 1 hr 30 min at 22-24 Celsius; corresponding to the following external morphological criteria: Advanced two cell stage. First cleavage groove has reached vegetal pole. Ventral side of blastomeres darker than dorsal side. Length: 1.4 - 1.5 mm.
Any of the developmental stages from fertilization to feeding.
Nieuwkoop and Faber stage 3; age 2 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Advanced four-cell stage. Second cleavage groove has reached vegetal pole. In animal view dorsal blastomeres usually smaller than ventral ones; the latter darker than the former. Length: 1.4 - 1.5 mm.
Nieuwkoop and Faber stage 4; age 2 hr 15 min at 22-24 Celsius; corresponding to the following external morphological criteria: Advanced eight cell stage. Dorsal micro- and macromeres usually smaller than ventral ones; dorsal micromeres less pigmented than ventral ones. Length: 1.4 - 1.5 mm.
Nieuwkoop and Faber stage 5; age 2 hr 45 min at 22-24 Celsius; corresponding to the following external morphological criteria: Advanced sixteen cell stage. Dorsal micromeres distinctly smaller and less pigmented than ventral ones. Macromeres entirely separated by cleavage grooves. Length: 1.4 - 1.5 mm.
Nieuwkoop and Faber stage 6; age 3 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Advanced thirty-two cell stage. Distinction between dorsal and ventral micromeres as in preceding stage. Length: 1.4 - 1.5 mm.
Nieuwkoop and Faber stage 7, 64-cell embryo; age 4 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Large-cell blastula stage. In animal view about 10 micromeres along meridian. Length: 1.4 - 1.5 mm.
Nieuwkoop and Faber stage 8, 128-cell embryo; age 5 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Medium-cell blastula stage. Surface not yet entirely smooth. Border of animal pigment cap more diffuse at dorsal than at lateral and ventral sides. Gradual transition in cell size from animal to vegetative pole. Length: 1.4 - 1.5 mm.
Nieuwkoop and Faber stage 9; age 7 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Fine-cell blastula stage. Animal cells smaller at dorsal than at ventral side. Border between marginal zone and vegetative field distinct, particularly dorsally, owing to difference in cell size. Length: 1.4 - 1.5 mm.
Nieuwkoop and Faber stage 10; age 9 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Initial gastrula stage. First indication of blastopore only by pigment concentration. No formation of groove. Length: 1.4 - 1.5 mm.
Nieuwkoop and Faber stage 11; age 11 hr 45 min at 22-24 Celsius; corresponding to the following external morphological criteria: Horse-shoe-shaped blastopore stage. Blastopore groove surrounding about half of future yolk plug and indicated at its ventral side; future yolk plug often rounded rectangular, slightly elongated in dorso-ventral direction, diameter more than two-fifths of diameter of egg (plus or minus 50 degrees of circumference). Length: 1.4 - 1.5 mm.
Nieuwkoop and Faber stage 12; age 13 hr 15 min at 22-24 Celsius; corresponding to the following external morphological criteria: Medium yolk plug stage. Yolk plug circular; diameter somewhat less than one fourth of diameter of egg (plus or minus 25 degrees). More and less pigmented fields radiating from yolk plug. Length: 1.4 - 1.5 mm.
Nieuwkoop and Faber stage 13; age 14 hr 45 min at 22-24 Celsius; corresponding to the following external morphological criteria: Slit-blastopore stage. Neural plate faintly delimited; slight elevation of its rostral part and slight flattening of its caudal part. Caudal part of median groove formed. Length: 1.5 - 1.6 mm.
Nieuwkoop and Faber stage 14; age 16 hr 15 min at 22-24 Celsius; corresponding to the following external morphological criteria: Neural plate stage. Cerebral part of neural plate bent downwards, with median elevation at rostral end of median groove. Initial elevation of neural folds, most pronounced in future nucal region. Blastopore always slit-shaped. Length: 1.5 - 1.6 mm.
Nieuwkoop and Faber stage 15; age 17 hr 30 min at 22-24 Celsius; corresponding to the following external morphological criteria: Early neural fold stage. Presumptive cement gland faintly circumscribed. Anterior part of neural plate roundish. Neural folds distinct, except medio-rostrally; initial formation of sharp inner ridges on neural folds in rhombencephalic region. Length: 1.5 - 1.6 mm.
Nieuwkoop and Faber stage 16; age 18 hr 15 min at 22-24 Celsius; corresponding to the following external morphological criteria: Mid neural fold stage. Anterior part of neural plate rectangular; darkly pigmented eye anlagen present; neural plate sharply constricted in the middle. Inner ridges on neural folds forming angle of about 90 degrees with neural plate in rhombencephalic region. Length: 1.5 - 1.6 mm.
Nieuwkoop and Faber stage 17; age 18 hr 45 min at 22-24 Celsius; corresponding to the following external morphological criteria: Late neural fold stage. Anterior part of neural plate oblong triangular, angles formed by eye anlagen. Neural folds approaching each other from blastopore up to anterior trunk region. Length: 1.5 - 1.6 mm.
Nieuwkoop and Faber stage 2-; age 1 hr 15 min at 22-24 Celsius; corresponding to the following external morphological criteria: Beginning of first cleavage. First cleavage groove has not yet reached vegetal pole. Length: 1.4 - 1.5 mm.
Nieuwkoop and Faber stage 6.5; age 3 hr 30 min at 22-24 Celsius; corresponding to the following external morphological criteria: Morula stage. About 48 blastomeres. In animal view about 6 micromeres along meridian. Length: 1.4 - 1.5 mm.
Nieuwkoop and Faber stage 10.25; age 10 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Early gastrula stage. First formation of dorsal blastopore groove; the groove is still straight. Length: 1.4 - 1.5 mm.
Nieuwkoop and Faber stage 10.5; age 11 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Crescent-shaped blastopore stage. Blastopore groove angular. Vegetal field slightly decreased in size, ventral border of future yolk plug indicated by pigment contraction. Length: 1.4 - 1.5 mm.
Nieuwkoop and Faber stage 11.5; age 12 hr 30 min at 22-24 Celsius; corresponding to the following external morphological criteria: Large yolk plug stage. Blastopore groove closed ventrally; yolk plug not yet quite circular. At ventral side concentrated superficial pigment still visible. Diameter of yolk plug about a third of diameter of egg (plus or minus 40 degrees). Length: 1.4 - 1.5 mm.
Nieuwkoop and Faber stage 12.5; age 14 hr 15 min at 22-24 Celsius; corresponding to the following external morphological criteria: Small yolk plug stage. Future position of neural plate and median groove indicated by darker pigment lines. Yolk plug usually ovoid, variable in size. Length: 1.4 - 1.5 mm.
Nieuwkoop and Faber stage 18; age 19 hr 45 min at 22-24 Celsius; corresponding to the following external morphological criteria: Neural groove stage. Anterior part of neural plate narrow, more or less club-shaped, often narrower towards rostral end. Parallel neural folds in trunk region very close to each other, not yet touching. Length: 1.5 - 1.6 mm.
Nieuwkoop and Faber stage 19; age 20 hr 45 min at 22-24 Celsius; corresponding to the following external morphological criteria: Initial neural tube stage. Neural folds touching each other, except for inconstant openings at anterior and posterior end and behind nucal region. Considerable lateral extension of brain. Lateral outline of embryo still convex. Length: 1.5 - 1.6 mm.
Nieuwkoop and Faber stage 20; age 21 hr 45 min at 22-24 Celsius; corresponding to the following external morphological criteria: Neural folds fused, suture still present. The two eye anlagen showing through dumb-bell-shaped, eyes hardly protruding. Beginning of stretching of embryos. Lateral outline flat. Length: 1.7 - 1.8 mm.
Nieuwkoop and Faber stage 21; age 22 hr 30 min at 22-24 Celsius; corresponding to the following external morphological criteria: Suture of neural tube completely closed. Delimitation of frontal field by pigment lines. Primary eye vesicles showing through in the form of two separate, obliquely placed oval spots; beginning of protrusion of eyes. Lateral outline of embryo just becoming concave, ventral outline flat. Length: 1.9 - 2.0 mm.
Nieuwkoop and Faber stage 22; age 24 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Distinct protrusion of eyes. Initial groove between jaw- and gill-areas only at latero-dorsal side. Lateral and ventral outlines of embryo slightly concave. Anal opening displaced to ventral side. Vitelline membrane becoming wider. Length: 2.0 - 2.2 mm.
Nieuwkoop and Faber stage 23; age 1 day, 45 min at 22-24 Celsius; corresponding to the following external morphological criteria: Jaw- and gill-areas completely separated by groove. Ventral outline of embryo more concave. Length: 2.2 - 2.4 mm.
Nieuwkoop and Faber stage 24; age 1 day, 2 hr 15 min at 22-24 Celsius; corresponding to the following external morphological criteria: Eyes protruding less far laterally than gill-area. Gill-area more prominent than jaw-area, gill-area not yet grooved. Ventral outline of embryo nicked. Tail bud discernible. Initial motor reactions to external stimulation. Length: 2.5 - 2.7 mm.
Nieuwkoop and Faber stage 25; age 1 day, 3 hr 30 min at 22-24 Celsius; corresponding to the following external morphological criteria: Eyes protruding equally far or further laterally than gill-area. Gill-area grooved. Invagination of otic vesicle indicated by pigment spot. Beginning of fin formation. Length: 2.8 - 3.0 mm.
Nieuwkoop and Faber stage 26; age 1 day, 5 hr 30 min at 22-24 Celsius; corresponding to the following external morphological criteria: otic vesicle protruding. Pronephros distinctly visible. Myotomes showing through for the first time. Fin somewhat broadened at dorso-caudal end of body. Beginning of spontaneous movements. Length: 3.0 - 3.3 mm.
Nieuwkoop and Faber stage 27; age 1 day, 7 hr 15 min at 22-24 Celsius; corresponding to the following external morphological criteria: Lateral flattening of eyes. Fin transluscent, except for region behind anus. Tail bud formation accentuated in lateral outline. Length: 3.4 - 3.7 mm.
Nieuwkoop and Faber stage 28; age 1 day, 8 hr 30 min at 22-24 Celsius; corresponding to the following external morphological criteria: Fin extending up to anus. Fin broadened and distinctly divided into outer transparent and inner translucent band. Length: 3.8 - 4.0 mm.
Nieuwkoop and Faber stage 29 and 30; age 1 day, 11 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Gray eye cup showing through for the first time. Fin transparent up to the base over its whole length. Tail bud distinct. Length: 4.0 - 4.5 mm.
Nieuwkoop and Faber stage 31; age 1 day, 13 hr 30 min at 22-24 Celsius; corresponding to the following external morphological criteria: Tail bud equally long as broad. Length: 4.2 - 4.8 mm.
Nieuwkoop and Faber stage 32; age 1 day, 16 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Eye cup horse-shoe-shaped, standing out distinctly. Length of tail bud about 1.5 times its breadth. Length: 4.5 - 5.1 mm.
Nieuwkoop and Faber stage 33 and 34; age 1 day, 20 hr 30 min at 22-24 Celsius; corresponding to the following external morphological criteria: Stomodeal invagination a shallow vertical groove. Dorsal part of eye more pigmented than ventral part; distinct melanophores in dorsal part. Melanophores appearing dorsally on the head and laterally in a row extending from just below the pronephros backwards. Length of tail bud about twice its breadth. Beginning of heart beat. Length: 4.7 - 5.3 mm.
Nieuwkoop and Faber stage 35 and 36; age 2 days, 2 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Stomodeal invagination roundish. Eye entirely black, choroid fissure nearly closed. Formation of two gill rudiments, anterior one nipple-shaped. Melanophores appearing on back. Posterior outline of proctodeum still curved. Length of tail bud about three times its breadth. Beginning of hatching. Length: 5.3 - 6.0 mm.
Nieuwkoop and Faber stage 37 and 38; age 2 days, 5 hr 30 min at 22-24 Celsius; corresponding to the following external morphological criteria: Stomodeal invagination much deeper, opening round. Both gill rudiments nipple-shaped, a branch of the anterior one indicated. Posterior outline of proctodeum straight, forming very obtuse angle with ventral border of tail myotomes. Melanophores spreading over tail. Length: 5.6 - 6.2 mm.
Nieuwkoop and Faber stage 39; age 2 days, 8 hr 30 min at 22-24 Celsius; corresponding to the following external morphological criteria: Melanophores appearing around nasal pits. Opening of stomodeal invagination transversely elongated. Melanophores on back arranged in a superficial and a deeper layer. Outlines of proctodeum and tail myotomes forming angle of about 135 degrees. Melanophores appearing along ventral edge of tail musculature. Length: 5.9 - 6.5 mm.
Nieuwkoop and Faber stage 40; age 2 days, 18 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Mouth broken through. Length of gills about twice their breadth, posterior one sometimes also showing a branch. Outlines of proctodeum and tail myotomes forming angles of 90 degrees. Beginning of blood circulation in gills. Length: 6.3 - 6.8 mm.
Nieuwkoop and Faber stage 41; age 3 days, 4 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Gills broader and flatter, more laterally directed. Formation of a left-rostral and a right-caudal furrow in yolk mass; torsion of interjacent part about 45 degrees; formation of conical proctodeum, forming angle of about 60 degrees with tail myotomes. Formation of fin rostral to proctodeum; ventral outline of yolk mass and proctodeum a smooth concave line. Length: 6.7 - 7.5 mm.
Nieuwkoop and Faber stage 42; age 3 days, 8 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Beginning of formation of opercular folds. Torsion of intestine about 90 degrees; proctodeum connected with yolk mass by short horizontal intestinal tube. Length: 7.0 - 7.7 mm.
Nieuwkoop and Faber stage 43; age 3 days, 15 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Lateral line system becoming visible externally. Cement gland losing its pigment. Torsion of intestine about 180 degrees; proctodeum narrower, arched or S-shaped. Length: 7.5 - 8.3 mm.
Nieuwkoop and Faber stage 44; age 3 days, 20 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Appearance of tentacle rudiments. Opercular folds protruding further. Coiling part of intestine showing S-shaped loop; torsion about 360 degrees. Blood-circulation in gills usually ceased (gills smaller). Length: 7.8 - 8.5 mm.
Nieuwkoop and Faber stage 45; age 4 days, 2 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Operculum partly covering gills, edge still straight. Intestine spiralized in ventral aspects, showing 1.5 revolutions. Beginning of feeding. Length: 8 - 10 mm.
Nieuwkoop and Faber stage 46; age 4 days, 10 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Edge of operculum becoming convex. Xantophores appearing on eye and abdomen. Intestine showing 2 to 2.5 revolutions. Hindlimb bud visible for the first time. Length: 9 - 12 mm.
Nieuwkoop and Faber stage 47; age 5 days, 12 hr at 22-24 Celsius; corresponding to the following external morphological criteria: Tentacles larger. Edge of operculum forming quarter of a circle. Xantophores forming opaque layer on abdomen. Intestine showing 2.5 to 3.5 revolutions. Hindlimb bud more distinct. Length: 12 - 15 mm.
Nieuwkoop and Faber stage 48; age 7.5 days at 22-24 Celsius; corresponding to the following external morphological criteria: Beginning of pigmentation around n. acusticus. Forelimb bud visible for the first time. Shining gold-coloured abdomen. Hindlimb bud semicircular in lateral aspect. Length: 14 - 17 mm.
Nieuwkoop and Faber stage 49; age about 12 days at 22-24 Celsius; corresponding to the following external morphological criteria: Melanophores usually appearing around thymus gland and nerves and blood vessels of head; xantophores appearing on pericard. Forelimb bud distinct. Hindlimb bud somewhat longer, distal outline still circular, no constrictions at base. Melanophores appearing on dorsal and ventral fin. Length: 17 - 23 mm.
Nieuwkoop and Faber stage 50; age about 15 days at 22-24 Celsius; corresponding to the following external morphological criteria: Forelimb bud somewhat oval-shaped in dorsal aspect. Hindlimb bud longer than broad, constricted at base, distal outline somewhat conical. Length: 20 - 27 mm.
Nieuwkoop and Faber stage 51; age about 17 days at 22-24 Celsius; corresponding to the following external morphological criteria: Tentacles much longer. Forelimb bud oval-shaped in lateral aspect. Hindlimb bud conical in shape, its length about 1.5 times its breadth; melanophores appearing on it. Length: 28 - 36 mm.
Nieuwkoop and Faber stage 52; age about 21 days at 22-24 Celsius; corresponding to the following external morphological criteria: Forelimb bud irregularly conical. Hindlimb bud showing first indication of ankle constriction and first sign of flattening of foot. Length: 42 - 56 mm.
Nieuwkoop and Faber stage 53; age about 24 days at 22-24 Celsius; corresponding to the following external morphological criteria: Fore- and hindlimbs in paddle stage. Hindlimb whithout foot somewhat longer than broad; 4th and 5th toe indicated. Length: 50 - 60 mm.
Nieuwkoop and Faber stage 54; age about 26 days at 22-24 Celsius; corresponding to the following external morphological criteria: All four fingers indicated; edge of hand slightly scalloped between fingers; melanophores appearing on forelimb. Length of hindlimb without foot nearly twice its breadth; all five toes indicated, the second only very slightly. Length: 58 - 65 mm.
Nieuwkoop and Faber stage 55; age about 32 days at 22-24 Celsius; corresponding to the following external morphological criteria: Hand pronated about 90 degrees; free parts of fingers about equally long as broad. Length of hindlimb without foot about 3 times its breadth; length of cartilages of 4th and 5th toe about 4 times their breadth. Length: 70 - 80 mm.
Nieuwkoop and Faber stage 56; age about 38 days at 22-24 Celsius; corresponding to the following external morphological criteria: Elbow and wrist clearly indicated; length of free parts of fingers 3 to 4 times their breadth. Length of cartilages of 4th and 5th toe about 6 times their breadth. Length: 70 - 100 mm.
Nieuwkoop and Faber stage 57; age about 41 days at 22-24 Celsius; corresponding to the following external morphological criteria: Pigment-free spot appearing above \"Stirnorgan\". Angle of elbow more than 90 degrees; fingers stretched out in forelimb atrium, their length about 7 times their breadth. Length: 75 - 105 mm.
Nieuwkoop and Faber stage 58; age about 44 days at 22-24 Celsius; corresponding to the following external morphological criteria: Forelimbs broken through. Guanophores appearing on abdomen and thighs (adult skin areas). All three claws present on hindlimbs. Length: 80 - 110 mm.
Nieuwkoop and Faber stage 59; age about 45 days at 22-24 Celsius; corresponding to the following external morphological criteria: Tentacles beginning to shrivel up. Stretched forelimb reaching down to base of hindlimb. Guanophores appearing near base of forelimb (adult skin area); anterior border of adult skin area on abdomen not yet sharp; appearance of irregular dark spots on back.
Nieuwkoop and Faber stage 60; age about 46 days at 22-24 Celsius; corresponding to the following external morphological criteria: N. olfactorius still longer than bulbus olfactorius. Guanophores appearing on lower jaw (adult skin area). Openings of gill chambers still wide. Distal half of fingers of stretched forelimb extending beyond base of hindlimb; forelimb still situated behind level of heart. Adult skin area of base of forelimb covered with guanophores; anterior border of adult skin area on abdomen sharper, reaching up to heart.
Nieuwkoop and Faber stage 61; age about 48 days at 22-24 Celsius; corresponding to the following external morphological criteria: Head narrower. Tentacles considerably shortened, mostly curved backwards. Length of n. olfactorius equal to diameter of bulbus olfactorius. 4th arterial arch seen just in front of adult skin area of forelimb. Openings of gill chambers considerably narrowed. Forelimb at level of posterior half of heart. Adult skin area on abdomen covering posterior half of heart. Fins considerably reduced.
Nieuwkoop and Faber stage 62; age about 49 days at 22-24 Celsius; corresponding to the following external morphological criteria: Head still somewhat broader than cranial part of trunk. Tentacles short, straight. N. olfactorius shorter than diameter of bulbus olfactorius. Corner of mouth still in front of eye. Thymus gland somewhat protruding. 3rd arterial arch (\"larval aorta\") seen at distance of its own diameter in front of adult skin area of forelimb. Opening of operculum reduced to curved slit. Forelimb at level of middle of heart. Anterior border of adult skin area on abdomen entirely sharp, mostly nicked medially. Ventral fin disappeared from abdomen.
Nieuwkoop and Faber stage 63; age about 51 days at 22-24 Celsius; corresponding to the following external morphological criteria: Head narrower than trunk. Tentacles mostly disappeared. Corner of mouth at level of caudal border of eye. \"Larval aorta\" and thymus gland no longer externally visible. Operculum closed. Adult skin areas on abdomen and lower jaw separated by narrow band of larval skin. Forelimb at level of anterior half of heart. Fin mostly perforated near anus. Tail still slightly longer than body.
Nieuwkoop and Faber stage 64; age about 53 days at 22-24 Celsius; corresponding to the following external morphological criteria: Corner of mouth well behind eye. Various adult skin areas joined almost everywhere, borderlines still clearly visible. Length of tail (from anus) is a third of body length.
Nieuwkoop and Faber stage 65; age about 54 days at 22-24 Celsius; corresponding to the following external morphological criteria: Borderlines between adult skin areas partly disappeared. Tail oblong triangular in dorsal aspect, length abouth one tenth of body length.
Nieuwkoop and Faber stage 66; age about 58 days at 22-24 Celsius; corresponding to the following external morphological criteria: Border lines between adult skin areas disappeared. Tail only a very small triangle, no longer visible from ventral side.
The stages from Nieuwkoop and Faber stage 54 to stage 66.
The stages from Nieuwkoop and Faber stage 29/30 to stage 44.
If an anatomical term has a starts_during or ends_during relationship to this stage term, this information is either unknown or has not yet been curated.
The period during which limb bud growth occurs, covering Nieuwkoop and Faber stage 45 to stage 54.
The period during which toe differentiation and rapid hind limb growth continue, covering Nieuwkoop and Faber stage 55 to stage 57.
The period during which tail resorption occurs, covering Nieuwkoop and Faber stage 58 to stage 66.
The stage of being a fully formed animal, following Nieuwkoop and Faber stage 66.