part of
develops from
ends during
preceded by
starts during
Xenopus anatomical entity
ectoderm
Primary germ layer that is the outer of the embryo's germ layers and gives rise to epidermis and neural tissue.
fin
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.
outer fin
inner fin
olfactory placode
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.
nasal placode
ear vesicle
otic vesicle
lower eyelid
lens
Transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina.
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.
brain
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.
forebrain
prosencephalon
The part of the brain that is the anterior of its three primary divisions and that includes the telencephalon and diencephalon.
telencephalon
diencephalon
midbrain
The part of the brain that is the middle of its three primary divisions.
mesencephalon
hindbrain
The part of the brain that is the posterior of its three primary divisions.
rhombencephalon
midbrain-hindbrain boundary
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.
MHB
isthmus
hypophysis
genital ridge
The precursor to the gonads.
spinal cord
Elongated, approximately cylindrical part of the central nervous system that lies in the vertebral canal and from which the spinal nerves emerge.
ventricular zone
roof plate
roofplate
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.
spinal cord roof
skin
integument
Surface structure that consists of the external membranous integument of the animal.
mandibular crest
hyoid crest
branchial crest
cranial ganglion
cranial ganglia
Ganglion that is located in the head.
epidermis
The outer epithelial layer of the external integument of the body that is derived from the embryonic epiblast.
epidermis outer layer
epidermis epithelial layer
periderm
vitelline membrane
ciliated cell
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.
stomodeal-hypophyseal primordium
cement gland
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.
hatching gland
frontal gland
zygote
Cell resulting from the fusion of male and female gametes at fertilization.
fertilized egg
animal cap
Ectodermal roof of the blastocoel.
animal ectoderm
animal cap inner layer
Sensorial layer of blastocoel roof ectoderm.
animal cap outer layer
Superficial layer of blastocoel roof ectoderm.
anatomical site
head region
epidermis inner layer
stratum germinativum
epidermis sensorial layer
neuroectoderm
neural ectoderm
presumptive central nervous system
Embryonic ectoderm that gives rise to nervous tissue.
neurectoderm
neuroectoderm outer layer
neuroectoderm inner layer
pre-chordal neural plate
The portion of neural plate anterior to the mid-hindbrain junction.
anterior neural plate
chordal neural plate
The portion of neural plate posterior to the mid-hindbrain junction.
posterior neural plate
notoplate
neural crest
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.
neural crest material
cement gland primordium
mesoderm
Primary germ layer that is the middle of the embryo's germ layers.
mesodermal mantle
dorsal aorta
cardinal vein
head mesoderm
trunk region
notochord
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.
hypochord
subnotochordal rod
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.
presomitic mesoderm
somitogenic mesoderm
somite
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).
somitic mesoderm
somites
pronephros
pronephric capsule
nephrostome
pronephric duct
heart
Internal, blood pumping organ ultimately composed of three chambers (two atria and one ventricle) and occupying a ventral position within the chest of the mature tadpole/frog.
myocardium
cardiac muscle
endocardium
blood island
ventral lateral plate mesoderm
VBI
ventral blood island
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.
marginal zone
ventral marginal zone
ventro-lateral marginal zone
dorso-lateral marginal zone
dorsal marginal zone
Marginal zone that is a key embryonic tissue region of the early gastrula stage embryo and that houses the Spemann-Mangold organizer.
organizer
DMZ
deep (mesenchymal) layer
involuting marginal zone
involuting marginal zone mesenchymal layer
deep involuting marginal zone
involuting marginal zone epithelial layer
superficial involuting marginal zone
bottle cell
Cell type that is first to migrate inwards at the blastopore during gastrulation.
blastopore lip
prechordal plate
head mesenchyme
forelimb region
hindlimb region
circumblastoporal collar
circumblastoporal region
involuted dorsal mesoderm
involuted ventral mesoderm
intermediate mesoderm
lateral plate mesoderm
ciliary marginal zone
tail region
upper blastopore lip
dorsal blastopore lip
lower blastopore lip
ventral blastopore lip
endoderm
Primary germ layer that lies remote from the surface of the embryo and gives rise to internal tissues such as gut.
entoderm
head endoderm
archenteron
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.
archenteron floor
archenteron roof
lateral line system
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.
lateral-line organs
lateral line stitches
pharyngeal arch
One of a series of bony or cartilaginous arches that develop in the walls of the mouth cavity and pharynx of the embryo.
visceral arch
pharyngeal arches
mandibular arch
first visceral arch
hyoid arch
second visceral arch
branchial arch
branchial arches
cardiovascular system
Anatomical system that has as its parts the heart and blood vessels.
liver diverticulum
visceral pouch 1
first visceral pouch
midgut
hindgut
pharyngeal cavity
post-anal gut
tail bud
tailbud
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.
chordoneural hinge
posterior wall of NEC
glomeral mesenchyme
glomerulus
corpuscle
Portion of tissue that consists of the precursors of the pronephric glomus or glomerulus; derived from the medial portion of the pronephric intermediate mesoderm.
germ cell
Cell type that is involved in the reproduction of the organism.
embryo
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.
artery
Any of the tubular branching vessels that carry blood from the heart through the body.
vein
Any of the tubular branching vessels that carry blood from the capillaries toward the heart.
capillary
Any of the smallest blood vessels connecting arterioles with venules.
respiratory system
Anatomical system that has as its parts the organs involved in breathing in respiration (breathing).
trachea
lung
Saccular thoracic organ that constitutes the basic respiratory organ.
external gill
bronchus
hematological system
Anatomical system that consists of the blood and blood forming tissues.
haematological system
hematopoietic system
bone marrow
blood
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.
alimentary system
Anatomical system that has as its parts the organs devoted to the ingestion, digestion, and assimilation of food and the discharge of residual wastes.
gut
digestive system
oral cavity
esophagus
oesophagus
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.
stomach
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.
intestine
small intestine
large intestine
liver and biliary system
liver
Vascular, glandular internal organ that secretes bile and causes important changes in many of the substances contained in the blood.
bile duct
Duct that carries bile from the liver to the small intestine.
hepatic duct
gall bladder
pancreas
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.
exocrine pancreas
Pancreatic tissue composed of acinar epithelial cells and ductal epithelium that manufacture the proteolytic enzymes and bicarbonate required for digestion.
mesentery
peritoneum
urogenital system
Anatomical system that has as its parts the organs concerned with the production and excretion of urine and those concerned with reproduction.
mesonephric kidney
adult kidney
opisthonephros
mesonephros
Organ that is the definitive adult kidney. It replaces the earlier pronephros, which degenerates as the mesonephros becomes functional in feeding stage tadpoles.
genital system
reproductive system
Anatomical system that has as its parts the organs concerned with reproduction.
urinary system
Anatomical system that has as its parts the organs concerned with the production and excretion of urine.
ureter
renal corpuscle
glomerus
mesonephric tubule
renal tubule
renal proximal convoluted tubule
loop of Henle
mesonephric collecting duct
renal distal convoluted tubule
urethra
bladder
male genitalia
The organs of the male reproductive system.
male genitals
female genitalia
The organs of the female reproductive system.
female genitals
testis
Reproductive organ that produces and releases sperm.
testes
endocrine system
Anatomical system that consists of the glands and parts of glands that produce endocrine secretions and help to integrate and control bodily metabolic activity.
Islets of Langerhans
endocrine pancreas
pineal gland
epiphysis
pineal organ
pituitary gland
thyroid
thymus
Anatomical structure of largely lymphoid tissue that functions in cell-mediated immunity by being the site where T cells develop.
adrenal gland
adrenal cortex
interrenal tissue
adrenal medulla
chromaffin cells
parathyroid
musculoskeletal system
Anatomical system that provides locomotion and physical support to the organism.
bone
The hard form of connective tissue that constitutes the majority of the skeleton.
cartilage
A type of dense connective tissue that is composed of specialized cells, chondrocytes, that produce a large amount of extracellular matrix.
joint
Anatomical cluster that consists of two or more adjacent bones or cartilages, which may be interconnected by various types of tissue.
muscle
A body tissue consisting of long cells that contract when stimulated and produce motion.
tendon
A fibrous, strong, connective tissue that connects muscle to bone.
skeletal muscle
A type of muscle used to create movement, by applying force to bones and joints.
smooth muscle
dermal system
Anatomical system that consists of the skin and its appendages.
nervous system
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.
peripheral nervous system
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.
PNS
eye
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.
eyes
cornea
The transparent front part of the eye that, together with the lens, refracts light.
globe
conjunctiva
sclera
iris
ciliary body
dorsolateral placode
cranial nerve II
Cranial nerve that runs to the eye.
optic nerve
auditory apparatus
external ear
middle ear
inner ear
Labyrinthine anatomical cluster that comprises sensory endorgans specialized for vestibular, auditory, and acoustico-vestibular sensation.
osseous labyrinth
bony labyrinth
membranous labyrinth
utricle
sacculus
saccule
lagena
cochlea
semicircular canal
vestibule
animal blastomere
Pigmented, smaller blastomere of the animal (upper) hemisphere of the cleaving embryo.
micromere
olfactory apparatus
animal hemisphere
archencephalic region
peripheral nerve
axial mesoderm
blastocoel anlage
blastocoel roof
blastopore
ganglion
ganglia
Portion of tissue that contains cell bodies of neurons and is located outside the central nervous system.
spinal ganglion
sympathetic chain
tympanum
auditory tube
auditory ossicle
central nervous system
CNS
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.
cortex
dermis
appendage
appendages
superficial (epithelial) layer
dermatome
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.
deuterencephalic region
ear placode
otic placode
Invagination of thickened epithelium near the hindbrain that gives rise to a spherically shaped ear vesicle.
auditory placode
vegetal part, early involuting
trigeminal placode
equatorial belt
eye primordium
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.
eye anlage
eye vesicle
optic cup
fasciculated network of fibrils
coelomic envelope
follicle cell
Cell type that forms a layer within an ovarian follicle that surrounds the oocyte.
follicle layer
foregut
germ plasm
germinal vesicle
cardiac mesoderm
Two migratory heart primordia that move ventrally during the course of neurulation, and whose fusion begins at the ventral midline at NF stage 16.
heart primordia
duodenum
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).
ileum
rectum
hepato-pancreatic duct
lens placode
posterior cardinal vein
mesonephric duct
Wolffian duct
colon
cloaca
cloacal chamber
mitochondrial aggregate
myocoelic slit
visceral pouch 2
second visceral pouch
neural groove
The median dorsal longitudinal groove formed in the embryo by the neural plate after the appearance of the neural folds.
neural plate
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.
posterior neural tube
visceral pouch 3
third visceral pouch
neurocoel
non-involuting marginal zone
visceral pouch 4
fourth visceral pouch
visceral pouch 5
fifth visceral pouch
oocyte
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).
oral evagination
ovary
Reproductive organ that produces and releases eggs.
paraxial mesoderm
Area of mesoderm at either side of the midline embryonic notochord that, on segmentation, forms the paired somites.
perivitelline space
pigment layer
polar body
primary oogonium
primary oogonia
pronephric mesenchyme
pronephric primordium
pronephric bulge
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.
pronephric anlage
visceral pouch 6
sixth visceral pouch
retinal layer
hypophyseal primordium
secondary oogonium
secondary oogonia
mouth primordium
sensorial layer of neurectoderm
deep layer of neurectoderm
somatic layer of lateral plate mesoderm
Jacobson's organ
organon vomeronasale
vomeronasal organ
VNO
An auxiliary olfactory sense organ involved in the detection of pheromones.
olfactory organ
sperm entry point
nasal pit
splanchnic layer of lateral plate mesoderm
choana
choanae
animal part, late involuting
vegetal blastomere
macromere
Unpigmented, larger blastomere of the vegetal (lower) hemisphere of the cleaving embryo.
vegetal hemisphere
vegetal yolk mass
visceral pouch
visceral pouches
pupil
epibranchial placode
pronephric nephron
late proximal tubule
early distal tubule
early proximal tubule
late distal segment
pronephric nephron segment S1
mesonephric mesenchyme
mesonephric nephron
The basic functional unit of the kidney.
nephron
neural fold
blastocoel
central endoderm
vegetal endodermal core
vegetal
animal
dorsal
ventral
superficial
deep
dorso-lateral
ventro-lateral
lateral
cranial placode
cranial placodes
floor plate
floorplate
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.
spinal cord floor
anterior neural tube
marginal zone (sensu neural)
anterior neural fold
head somite
occipital somite
cranial somite
Any of the transient, degenerating occipital somites.
trunk somite
myotome
Somitic compartment that is a precursor of muscle.
myotomes
epicardium
glomus
Properly called a glomus as it extends over multiple body segments.
glomera
The filtration unit of the pronephric kidney.
trunk neural crest
trunk crest
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.
sensorial layer
The inner layer of ectoderm.
profundus ganglion
profundus ganglia
hypobranchial placode
Derivative of ectodermal thickening ventral to second and third pharyngeal pouches. Gives rise to neurons of unknown fate.
left spleen primordium
Primordium of the spleen, which goes on to form the spleen proper, while the right splenic promordium degenerates.
right spleen primordium
Transient splenic primordia that degenerates by NF stage 40.
spleen
Internal lymphoid organ derived from left spleen primordia beginning at NF stage 48.
coelomic epithelium
The epithelial lining of the coelom.
Mullerian duct
mesonephric early proximal tubule
Structure that is equivalent to the convoluted proximal tubule of metanephric nephrons.
mesonephric late proximal tubule
proximal straight segment
Structure that is the mesonephros nephron's equivalent to the straight proximal segment of a metanephric nephron.
mesonephric early distal tubule
ascending limb
straight distal segment
The mesonephric equivalent of the ascending limb, or straight distal segment, of metanephric nephrons.
mesonephric late distal segment
The site of bicarbonate resorption in the adult kidney. It is equivalent to the convoluted distal segment of metanephric nephrons.
fused heart primordium
heart primordium
endocardial tube
ventral aorta
left channel of ventral aorta
right channel of ventral aorta
aortic arch
aortic arches
aortic arch 1
first aortic arch
aortic arch 2
second aortic arch
aortic arch 3
third aortic arch
external carotid artery
larval aorta
secondary vessel
aortic arch 5
fifth aortic arch
aortic arch 6
sixth aortic arch
posterior palatine artery
aortic arch 4
fourth aortic arch
vascular endothelium
vascular endothelia
angioblasts
arterial endothelium
venous endothelium
arteria iliaca communis
coeliaco-mesenteric artery
occipitovertebral artery
caudal artery
arteria subclavia
internal carotid artery
cerebral artery
opthalmic artery
anterior palatine artery
arteria mesenterica posterior
anterior lymph heart
posterior lymph heart
Precursor to the lymph vessels, consisting of four pairs initially.
duct of Cuvier
common cardinal vein
dorsal lymph space
lymph vessel
lymphatic vessel
A vessel that contains or conveys lymph.
omphalomesenteric vein
capillary system of liver
musculoabdominal vein
external jugular
lateral postcardinal vein
mesonephric sinus
internal jugular
anterior cardinal vein
medial cardinal vein
pronephric sinus
interrenal vein
hepatic vein
posterior vena cava
gastric vein
caudal vein
subinterstitial vein
portal vein
tail vein
pulmonary vein
medial abdominal vein
head somite 1
somite W
Transient occipital somite that exists from NF stages 17 to 26 only.
sclerotome
sclerotomes
Somitic compartment that is a precursor of the axial skeleton.
tendon fibroblast
sclerotomal cartilage
head somite 2
somite X
Transient occipital somite that exists from NF stages 18 to 29 only.
head somite 3
Transient occipital somite that exists from NF stages 18 to 29/30 only.
somite Y
head somite 4
Transient occipital somite that exists from NF stages 19 to late 30's.
somite Z
trunk somite 1
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.
fifth somite
trunk somite 2
Trunk somite that is initially the sixth somite.
trunk somite 3
trunk somite 4
trunk somite 5
trunk somite 6
trunk somite 7
sclerotomal mesenchyme
notochordal sheath
trunk somite 8
trunk somite 9
trunk somite 10
trunk somite 11
trunk somite 12
trunk somite 13
trunk somite 14
trunk somite 15
trunk somite 16
Trunk somite that forms at NF stage 28, by which time head somite 1 has degenerated.
trunk somite 17
cranial nerve I
olfactory nerve
Cranial nerve that supplies the nasal organ.
gasserian ganglion
gasserian ganglia
trigeminal ganglion
trigeminus ganglion
trigeminal ganglia
cephalic nerve
Rathke's pouch
tooth
dentition
teeth
death
The end of the animal's life.
coelomic filter chamber
coelom
lateral line placode
lateral line placodes
infraorbital lateral line primordium
supraorbital lateral line
trunk lateral line
thyroid primordium
taste bud
tongue
branchial arch 1
third visceral arch
first branchial arch
gill primordium
branchial arch 2
second branchial arch
fourth visceral arch
epithelial body
branchial arch 3
fifth visceral arch
third branchial arch
ultimobranchial body
branchial arch 4
fourth branchial arch
sixth visceral arch
liver parenchyme
biliary tree
pyloric sphincter
occipital lateral line
infraorbital lateral line
hyomandibular lateral line
trunk placode
dorsal lateral line
middle lateral line
ventral lateral line
caudal lateral line
dorsal pancreatic bud
dorsal fin
unicellular gland
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.
xanthophore
iridophore
guanophore
choroid fissure
A break in the continuity of the optic cup where the two sides of the cup meet.
optic stalk
cranial neural crest
head crest
Neural crest that is part of the head.
lung primordium
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.
lateral diverticula
circulatory system
vasculature
Anatomical system that has as its parts the blood and lymph vessels.
blood vessel
Any of the vessels through which blood circulates in the body.
Stirnorgan
frontal organ
facial muscle
melanophore
melanocyte
A pigment cell that contains melanin, a brownish-black pigment.
rectal diverticulum
rectal diverticula
abdominal myoblast
portion of connective tissue
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.
anterior lymph sac
rostral lymph sac
proctodeum
anus
proctodaeum
Inward fold on the surface of the embryonic ectoderm that develops into part of the anal passage.
elastica externa
Notochordal sheath or membrane. Its first indication is at NF stage 24, and it is a distinct membrane by NF stage 28.
notochordal epithelium
first pancreatic bud
second pancreatic bud
ventral pancreatic bud
pronephric kidney
Organ that serves as a transient kidney, providing osmoregulation during early developmental stages and then degenerating during metamorphosis.
anatomical structure
Material anatomical entity that has inherent 3D shape and is generated by coordinated expression of the organism's own genome.
anatomical group
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 system
Anatomical group that has as its parts distinct anatomical structures interconnected by anatomical structures at a lower level of granularity.
unspecified
Annotation of data with this anatomy term indicates that a structure or tissue was not specified by the investigator.
whole organism
Anatomical structure that is an individual member of Xenopus laevis.
female organism
Gonochoristic organism that can produce female gametes.
male organism
Gonochoristic organism that can produce male gametes.
anatomical entity in vitro
activin-induced ectoderm
disaggregated/reaggregated ectoderm treated with activin
aorta
primary germ layer
embryonic germ layer
germ layer
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.
cell
Anatomical structure that has as its parts a maximally connected cell compartment surrounded by a plasma membrane.
organism subdivision
Anatomical structure that is a primary subdivision of the whole organism.
body part
pigment cell
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.
chromatophore
myoblast
Embryonic (precursor) cell of the myogenic lineage that develops from the mesoderm.
blastomere
Undifferentiated cell that is produced by early cleavages of the fertilized egg (zygote).
blastoderm cell
fibroblast
A connective tissue cell that secretes an extracellular matrix rich in collagen and other macromolecules.
primary spermatogonium
primary spermatogonia
spermatocyte
The developing male gamete.
secondary spermatogonium
secondary spermatogonia
spinal cord neuron
Rohon-Beard neuron
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.
Rohon Beard cell
neuron
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.
nerve cell
head
Organism subdivision that is the part of the body consisting of the cranial and pharyngeal regions.
trunk
Organism subdivision that is the part of the body posterior to the head and anterior to the tail.
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.
limb
Organism subdivision that has as its parts the jointed appendages used for locomotion and manipulation.
surface structure
Organism subdivision that is the collection of anatomical structures on the body surface.
mouth
The opening of the head through which food passes into the body.
forelimb
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.
hind limb
hindlimb
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.
digit
One of several most proximal parts of a limb.
nostril
Surface structure that provides one of the small external openings of the head that give passage to air for breathing.
viscus
viscera
An internal organ of the body; especially: one (as the heart, liver, or intestine) located in the great cavity of the trunk proper.
hind digit
A digit that is one of several most proximal parts of a hind limb.
fore digit
A digit that is one of several most proximal parts of a forelimb.
multi-tissue structure
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.
simple organ
Multi-tissue structure that is not part of a compound organ.
compound organ component
Multi-tissue structure that is part of a compound organ.
portion of tissue
Anatomical structure that consists of similar cells and intercellular matrix, aggregated according to genetically determined spatial relationships.
compound organ
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.
embryonic structure
An anatomical structure that exists only before the organism is fully formed.
primordium
An embryonic structure that is the rudiment or commencement of a part or organ.
endomesoderm
Primary germ layer that can give rise to both mesoderm and endoderm.
mesendoderm
epithelium
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.
mesenchyme
Portion of tissue consisting of loosely organized undifferentiated mesodermal cells that give rise to such structures as connective tissues, blood, lymphatics, bone, and cartilage.
nerve
Portion of tissue that consists of a fasciculated group of axons.
egg
A mature female germ cell that is capable of initiating formation of a new individual by fusion with a male gamete.
unfertilized egg
ovum
adipose tissue
Connective tissue in which fat is stored.
fat body
dorsal lateral plate region
aorta-gonads-mesonephros region
AGM region
Region located near the pronephros and pronephric ducts that is a site of hematopoiesis in the embryo.
DLP
oviduct
Keller explant
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.
stem cell
A relatively undifferentiated cell that retains the ability to divide and proliferate throughout life to provide progenitor cells that can differentiate into specialized cells.
hematopoietic stem cell
HSC
anterior
posterior
larval structure
chondrocranium
Structure consisting of a cartilaginous skull that begins to form during early tadpole stage.
cartilaginous skull
skeletal system
Anatomical system that provides physical support to the organism.
forelimb skeleton
Skeletal structure of the paired, anterior appendages.
hind limb skeleton
Skeletal structure of the paired, posterior appendages.
pectoral girdle
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.
shoulder girdle
pelvic girdle
Arched skeletal structure that supports the hind limbs, begins to develop at NF stage 50, and is ossified by NF stage 66.
forelimb bud
hind limb bud
fore epipodium
Segment of the forearm corresponding to the radio-ulna.
fore mesopodium
Segment of the forearm corresponding to the carpus.
hind propodium
Segment of the hind limb corresponding to the femur, which begins to ossify at NF stage 55.
hind metapodium
Segment of the leg corresponding to the metatarsus.
fore propodium
Segment of the forelimb corresponding to the humerus.
hind epipodium
foot skeleton
Segment of the hind limb corresponding to the tibia-fibula, which undergoes ossification from NF stage 56 to stage 66.
postcranial axial skeleton
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.
axial skeleton
vertebral column
cranium
cranial skeleton
cervical vertebra
presacral vertebra
sacral vertebra
caudal vertebra
urostyle
larynx
sucker
braincase and otic capsule skeleton
lower jaw
Meckel's cartilage
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.
suspensorium
upper jaw
seminiferous tubule
cranial nerve
Any of the major paired nerves of the head region.
cranial nerves
cranial nerve III
Cranial nerve that runs to the eye muscles.
oculomotor nerve
cranial nerve IV
pathetic nerve
trochlear nerve
Cranial nerve, also known as the pathetic nerve, that runs to the eye muscles.
cranial nerve V
trigeminal nerve
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 VI
abducent nerve
abducens nerve
Cranial nerve, also known as the abducent nerve, that runs to the eye muscles.
cranial nerve VII
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).
facial nerve
cranial nerve VIII
Cranial nerve that runs to the ear.
auditory nerve
cranial nerve IX
glossopharyngeal nerve
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 X
vagus nerve
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).
cerebellum
fourth ventricle
IVth ventricle
medulla oblongata
spinal nerve
transverse process
claw
Anatomical structure consisting of a small, pointed keratinized appendage at the end of each of the three inner toes of the hind limbs.
myotome of head somite 1
myotome of head somite 2
myotome of head somite 3
myotome of head somite 4
myotome of trunk somite 1
myotome of trunk somite 2
myotome of trunk somite 3
myotome of trunk somite 4
sclerotome of head somite 4
sclerotome of trunk somite 1
sclerotome of trunk somite 2
sclerotome of trunk somite 3
sclerotome of trunk somite 4
myotome of trunk somite 5
myotome of trunk somite 6
myotome of trunk somite 7
myotome of trunk somite 8
sclerotome of trunk somite 5
sclerotome of trunk somite 6
sclerotome of trunk somite 7
sclerotome of trunk somite 8
myotome of trunk somite 9
sclerotome of trunk somite 9
sclerotome of trunk somite 10
myotome of trunk somite 10
sclerotome of trunk somite 11
myotome of trunk somite 11
sclerotome of trunk somite 12
myotome of trunk somite 12
sclerotome of trunk somite 13
myotome of trunk somite 13
sclerotome of trunk somite 14
myotome of trunk somite 14
sclerotome of trunk somite 15
myotome of trunk somite 15
sclerotome of trunk somite 16
myotome of trunk somite 16
sclerotome of trunk somite 17
myotome of trunk somite 17
tail somite
amphibian papilla
basilar papilla
gonad
Reproductive organ that produces and releases eggs (ovary) or sperm (testis).
spermatozoon
A mature male germ cell that develops from a spermatid.
sperm
spermatozoa
germ line cell
primordial germ cell
PGC
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.
primitive germ cell
gamete
A mature male or female germ cell.
spermatid
immune system
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.
larval immune system
adult immune system
lymphocyte
A cell of the B cell, T cell, or natural killer cell lineage.
natural killer cell
NK cell
T cell
B cell
thymocyte
anatomical cluster
Anatomical group that has its parts adjacent to one another.
limb bud
acellular anatomical structure
Anatomical structure that consists of cell parts and cell substances and together does not constitute a cell or a tissue.
basal lamina
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.
solid compound organ
Compound organ that does not contain macroscopic anatomical spaces.
cavitated compound organ
Compound organ that contains one or more macroscopic anatomical spaces.
appendicular skeleton
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.
fore metapodium
Segment of the forearm corresponding to the metacarpus.
hind mesopodium
Segment of the leg corresponding to the tarsus.
dermatocranium
Cranium which consists of dermally derived bones.
neurocranium
orbital region
Anatomical cluster that is part of the cranium and provides structural support for the eye.
olfactory region
Anatomical cluster that is located in the anterior region of the cranium and provides structural support for the olfactory organ.
occipital region
Anatomical cluster that is located in the posterior region of the cranium and forms the margin of the foramen magnum and occipital condyles.
sphenoid region
Anatomical cluster that forms the floor and side walls of the middle part of the cranium.
otic region
Anatomical cluster that is a posterolateral part of the cranium and structurally supports the vestibuloauditory system.
splanchnocranium
Regional skeletal system of the jaws, hyoid and branchial arches.
hyoid arch skeleton
dorsal hyoid arch skeleton
ventral hyoid arch skeleton
branchial arch skeleton
branchial arch skeleton 1
branchial arch skeleton 2
branchial arch skeleton 3
branchial arch skeleton 4
anatomical direction
anatomical region
medial
proximal
distal
anatomical space
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.
left atrium
right atrium
cardiac ventricle
sensory system
A part of the nervous system responsible for processing sensory information.
vestibuloauditory system
The sensory system used for balance and hearing.
olfactory system
The sensory system used for olfaction (the sense of smell).
gustatory system
The sensory system used for the sense of taste.
visual system
The sensory system used for sight.
lymphatic system
gut epithelium
oral epithelium
pharyngeal epithelium
dental epithelium
neural tube
chondrocyte
Polymorphic cell type that forms cartilage.
podocyte
Cell type that is a component of the glomus.
Xenopus developmental stage
NF stage 1
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.
early tailbud
The stages from Nieuwkoop and Faber stage 22 to stage 28.
blastula
The stages from 64-cell embryo to Nieuwkoop and Faber stage 9, during which the solid morula acquires an internal cavity.
cleavage
The stages from 2-cell to 64-cell embryo, during which the zygote undergoes synchronous divisions into 2, 4, 8, 16, etc. blastomeres.
gastrula
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.
neurula
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.
tailbud stage
Any of the developmental stages from Nieuwkoop and Faber stage 20 to stage 44 (feeding), including the beginning of hatching (NF stage 35/36).
tadpole
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.
larva
adult
The stage of being a fully formed animal, following Nieuwkoop and Faber stage 66.
juvenile
The stage of being a sexually immature adult animal.
NF stage 2 (2-cell)
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.
2-cell stage
embryonic stage
Any of the developmental stages from fertilization to feeding.
NF stage 3 (4-cell)
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.
4-cell stage
NF stage 4 (8-cell)
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.
8-cell stage
NF stage 5 (16-cell)
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.
16-cell stage
NF stage 6 (32-cell)
32-cell stage
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.
NF stage 7
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.
64-cell stage
NF stage 8
128-cell stage
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.
NF stage 9
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.
NF stage 10
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.
NF stage 11
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).
NF stage 12
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.
NF stage 13
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.
NF stage 14
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.
NF stage 15
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.
NF stage 16
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.
NF stage 17
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.
NF stage 2-
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.
NF stage 6.5
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.
morula
NF stage 10.25
NF stage 10+
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; groove still straight.
NF stage 10.5
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.
NF stage 11.5
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).
NF stage 12.5
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.
NF stage 18
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.
NF stage 19
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.
NF stage 20
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.
NF stage 21
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.
NF stage 22
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.
NF stage 23
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.
NF stage 24
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.
NF stage 25
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.
NF stage 26
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.
NF stage 27
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.
NF stage 28
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.
NF stage 29 and 30
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.
NF stage 31
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.
NF stage 32
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.
NF stage 33 and 34
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.
NF stage 35 and 36
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.
NF stage 37 and 38
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.
NF stage 39
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.
NF stage 40
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.
NF stage 41
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.
NF stage 42
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.
NF stage 43
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.
NF stage 44
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).
NF stage 45
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.
NF stage 46
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.
NF stage 47
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.
NF stage 48
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.
NF stage 49
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.
NF stage 50
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.
NF stage 51
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.
NF stage 52
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.
NF stage 53
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.
NF stage 54
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.
NF stage 55
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.
NF stage 56
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.
NF stage 57
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.
NF stage 58
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.
NF stage 59
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.
NF stage 60
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.
NF stage 61
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.
NF stage 62
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.
NF stage 63
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.
NF stage 64
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.
NF stage 65
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.
NF stage 66
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.
metamorphosing tadpole
The stages from Nieuwkoop and Faber stage 54 to stage 66.
late tailbud
The stages from Nieuwkoop and Faber stage 29/30 to stage 44.
unspecified stage
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.
premetamorphosis
The period during which limb bud growth occurs, covering Nieuwkoop and Faber stage 45 to stage 54.
prometamorphosis
The period during which toe differentiation and rapid hind limb growth continue, covering Nieuwkoop and Faber stage 55 to stage 57.
climax
The period during which tail resorption occurs, covering Nieuwkoop and Faber stage 58 to stage 66.