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{{Rugh1951 header}}
 
{{Rugh1951 header}}
==Appendix: Chronological Summary of Organ Anlagen Appearance of Rana pipiens==
+
=Appendix: Chronological Summary of Organ Anlagen Appearance of ''Rana pipiens''=
  
Stage 17: 3 mm. total body length.
+
==Stage 17: 3 mm total body length==
  
Blastopore closes, neurenteric canal transient, neural tube closed  
+
Blastopore closes, neurenteric canal transient, neural tube closed but no differentiation of central nervous system, body elongated with back curve changing from convex to concave, myotomes evident but movement by surface ciliation. Internally most of major organ systems begin to appear including heart mesenchyme, visceral arches,  
but no differentiation of central nervous system, body elongated with  
+
and lateral plate mesoderm, pronephros, hypochordal rod, sense and gill plates, optic vesicles, and both auditory and olfactory placodes.  
back curve changing from convex to concave, myotomes evident but  
 
movement by surface ciliation. Internally most of major organ systems begin to appear including heart mesenchyme, visceral arches,  
 
and lateral plate mesoderm, pronephros, hypochordal rod, sense and  
 
gill plates, optic vesicles, and both auditory and olfactory placodes.  
 
  
Stage 18: 4 mm. total body length.
+
==Stage 18: 4 mm total body length==
  
First evidence of muscular movement, primary brain differentiations, infundibulum and hypophysis still separate, lateral line nerve  
+
First evidence of muscular movement, primary brain differentiations, infundibulum and hypophysis still separate, lateral line nerve develops from vagus placode, auditory placode becomes separated from head ectoderm, lens placode formed, ventral roots develop from spinal cord, hypochordal rod separated from gut, notochord becomes vacuolated and acquires an elastic and a fibrous coating from sclerotome, oesophageal plug formed, dorsal aorta paired anteriorly and single posteriorly, vitelline veins prominent and functional.  
develops from vagus placode, auditory placode becomes separated  
 
from head ectoderm, lens placode formed, ventral roots develop from  
 
spinal cord, hypochordal rod separated from gut, notochord becomes  
 
vacuolated and acquires an elastic and a fibrous coating from sclerotome, oesophageal plug formed, dorsal aorta paired anteriorly and  
 
single posteriorly, vitelline veins prominent and functional.  
 
  
Stage 19: 5 mm. total body length.
+
==Stage 19: 5 mm total body length==
  
Epiphysis well developed as evagination of prosencephalon, infundibulum, and hypophysis are approximated in position, thyroid  
+
Epiphysis well developed as evagination of prosencephalon, infundibulum, and hypophysis are approximated in position, thyroid evagination develops, trigeminal nerve from first cranial crest and placode, facial and auditory nerves from second cranial crest and placode, lens vesicle separated from head ectoderm, 45 pairs of somites developed (by 5.5 mm. stage), 32 of which are in tail, muscles with fibrillae, sclerotome abundant, heart differentiated and beating.
evagination develops, trigeminal nerve from first cranial crest and  
 
placode, facial and auditory nerves from second cranial crest and  
 
placode, lens vesicle separated from head ectoderm, 45 pairs of  
 
somites developed (by 5.5 mm. stage), 32 of which are in tail, muscles  
 
with fibrillae, sclerotome abundant, heart differentiated and beating.  
 
  
 +
[[File:Rugh_167.jpg|400px]]
  
 +
Parts of the middle and inner ear of the frog. Schematized drawing.
  
Posterior choroid plexus
+
==Stage 20: 6 mm total body length==
Rhombocoel
 
  
 +
Hatches, oral suckers at maximum development, blood system well developed, including endocardium, myocardium, and pericardium of the heart, pulmonary veins develop but do not function, gill circulation abundant, blood islands numerous, lymph hearts first appear at level of somites III and IV, pronephros with glomi and segmental duct become partially embedded in posterior cardinal veins, a solid rod of ectoderm cells extend from olfactory pit to pharynx, four cranial ganglionic masses appear, optic nerve develops from neuroblasts of retina, and sympathetic nervous system arises from neural crests.
  
 +
==Stage 21: 7 mm total body length==
  
 +
Transition from larva to tadpole, mouth open, cornea transparent, cerebral hemispheres and vesicles differentiated, endolymphatic duct open to surface, heart folding upon itself, paired and metameric dorsal root ganglia, interatrial septum separates auricles, sex cell (genital) ridge appears.
  
Auditory capsule (cartilage)
 
Cranial nerve VIII
 
  
Semicircular canals (inner ear)
+
==Stage 22: 8 mm total body length==
Stapedial plate
 
Columella
 
  
Annulus tympanicus
+
Heart partitions completed and heart differentiated, circulation reaches tail fin, lung buds develop, sub-notochordal rod disappears and mesonephros begins to form.
 
 
Tympanum
 
  
Middle ear vestibule
 
Perilymph space
 
  
Eustachian tube
 
(hyomandibular pouch'
 
  
Head mesenchyme
+
[[File:Rugh 168.jpg|thumb|500px]]
  
Cranial cartilage
+
Olfactory organs of Rana pipiens tadpoles at 20 mm total body length.
  
Heart mesoderm
+
{|
Parts of the middle and inner ear of the frog, schematized drawing.
+
|
 +
* af - Anterior choanal fold
 +
* cc - Choanal canal
 +
* ct - Cornu trabeculae
 +
* cv - Christa ventralis
 +
|
 +
* ec - Entrance canal
 +
* ig - Inferior canal
 +
* ir - Inferior recess
 +
* b - Lateral appendix
 +
|
 +
* Ig - Lateral groove
 +
* pf - Posterior pharyngeal fold
 +
* pr - Posterior recess
 +
* sc - Superior cavity
 +
|}
  
Stage 20: 6 mm. total body length.
+
==Stage 23: 9 mm total body length==
  
Hatches, oral suckers at maximum development, blood system well
+
Mouth developing with embryonic teeth, opercular fold begins backward growth, tongue anlage appears, carotid glands develop from ventral wall of first branchial pouch, epithelioid bodies from wall of second and third branchial pouches, oesophageal plug disappears, pancreas anlage is formed, pharyngeal arteries as well as subclavians grow from dorsal aorta, mesenteric and lumbar arteries appear, parachordal plate develops in floor of cranium, brain develops anterior choroid plexus, optic lobes, and cerebellum, cranial nerves (except abducens) well developed including all parts of trigeminal.  
developed, including endocardium, myocardium, and pericardium
 
of the heart, pulmonary veins develop but do not function, gill circulation abundant, blood islands numerous, lymph hearts first appear  
 
at level of somites III and IV, pronephros with glomi and segmental
 
duct become partially embedded in posterior cardinal veins, a solid
 
rod of ectoderm cells extend from olfactory pit to pharynx, four cranial ganglionic masses appear, optic nerve develops from neuroblasts
 
of retina, and sympathetic nervous system arises from neural crests.  
 
  
Stage 21: 7 mm. total body length.
+
==Stage 24: 10 mm total body length==
  
Transition from larva to tadpole, mouth open, cornea transparent,  
+
Atrophy of mucous glands, mouth with horny jaws and cornified lips takes in vegetable diet, intestine long and looped, operculum closed on right side, thyroid bifurcates and separates from pharynx, spleen anlage appears, two or three branchial clefts break through, mesonephros developing, utricle separated from saccule by oblique partition, all semi-circular canals indicated, optic lobes formed, median cardinal vein appears, and posterior vena cava begins to develop.  
cerebral hemispheres and vesicles differentiated, endolymphatic duct
 
open to surface, heart folding upon itself, paired and metameric
 
dorsal root ganglia, interatrial septum separates auricles, sex cell
 
(genital) ridge appears.  
 
  
 +
==Stage 25: 11 mm total body length==
  
 +
Cilia lost except on tail, operculum completed, cornification of horny rasping papillae of jaws and lips, oesophagus differentiated from stomach, lung buds invested with mesenchyme, pronephros large and conspicuous, retina develops rods and cones, olfactory apparatus develops lateral appendix, internal choanae open, olfactory nerve is derived from olfactory lobe neuroblasts, and abducens is formed from neuroblasts of medulla.
  
Stage 22: 8 mm. total body length.
+
==12 mm total body length stage==
  
Heart partitions completed and heart differentiated, circulation reaches tail fin, lung buds develop, sub-notochordal rod disappears and mesonephros begins to form.  
+
Olfactory tube develops complete lumen from external nares to internal choanae, thymus separates from dorsal part of first branchial pouch and comes to lie posterior to tympanic membrane near mandibular muscles, maximum development of the pronephros which degenerates by 20 mm. stage, cortical (interrenal) adrenal arises from peritoneum in vicinity of cardinal veins, paired gonad primordia prominent.  
  
  
 +
==15 mm total body length stage==
  
Olfactory organs of Rana pipiens tadpoles at 20 mm. total body length.  
+
Notochordal cartilage sheath develops, vertebrae begin to appear, saccule gives rise to lagena (cochlea) and to a basilar chamber, sensory patches appear in ear epithelium, lateral line organ fully developed, mesonephric tubules associated with median cardinal vein.  
  
 +
==Metamorphosis at 75 to 90 days==
  
(af) Anterior choanal fold,  
+
Loss of horny jaws, widening of mouth, shortening of gut and changing of its histology to conform with a change from vegetable diet to an omnivorous diet, loss of tail with its 32 pairs of spinal nerves and development of two pairs of legs, shedding of larval skin, disappearance of lateral line system as frog leaves aquatic environment, loss of caudal veins, full development of tongue, active functioning of endocrine glands (particularly thyroid and pituitary), and appearance of differentiated gonads containing maturing gametes.
  
(cc) Choanal canal,
+
{|
 +
|
 +
===Stages in the metamorphosis of Rana pipiens===
  
(ct) Cornu trabeculae.  
+
'''(Stage I)''' The oral sucker elevations have completely disappeared. Four rows of labial teeth are present, one pre-oral and three post-oral. Chromatophores have appeared and become numerous on the dorsal and lateral surfaces, and extend progressively ventrad. The limb bud is visible as a faintly circumscribed elevation in the groove between the base of the tail and the belly wall. The height of the elevation is less than half the diameter of the disk.  
  
(cv) Christa ventralis.
 
  
(ec) Entrance canal,  
+
'''{Stage II)''' The height of the limb bud elevation (i.e., the length of the bud) is equal to half of its diameter. The first row of post-oral labial teeth is usually at the middle to form a pair of crescents. On the dorsal surface of the head the lateral line system is becoming conspicuous as pigment-free lines, especially in darkly pigmented individuals. The melanophore patches covering the gill region on either side usually meet in a narrow band ventral to the heart.
  
(ig) Inferior canal.
 
  
 +
'''(Stage III)''' The length of the limb bud is equal to its diameter, and it continues to grow both in length and diameter at an approximately equal rate. This stage is relatively long in duration. (Stage IV) The length of the limb bud is equal to one and a half times its diameter.
  
(ir) Inferior recess.
 
  
(b) Lateral appendix.  
+
'''(Stage V)''' The length of the limb bud is twice its diameter. The distal half of the bud is bent ventrad. There is no flattening of the tip. (Continued on facing page.)
  
(Ig) Lateral groove.  
+
| [[File:Rugh_169.jpg|600px]]
 +
|}
  
(pf) Posterior pharyngeal fold.
+
{|
 +
|
 +
===Stages in the metamorphosis of Rana pipiens===
  
(pr) Posterior recess.  
+
(Stage VI) The distal end of the limb bud is flattened mediolaterally to form the foot paddle. There are no interdigital indentations of the paddle margin.
  
(sc) Superior cavity.
 
  
 +
(Stage VII) The fourth and fifth toe prominences are separated by a slight indentation of the margin of the foot paddle.
  
  
(Courtesy, Ruth Cooper, /. Exper. ZooL, 93:415.)
+
(Stage VIII) The margin of the foot paddle is indented between toes 5-4 and 4-3. The patch of melanophores on the limb lengthens into a streak extending from above the knee bend to foot.
  
  
 +
(Stage IX) The margin of the foot paddle is indented between toes 5-4, 4-3, and 3-2. Usually spontaneous movements of the limb proper (flexion of the knee and ankle) can be seen under binocular microscopes. These movements may not appear until the following stage. Shortly after such movements appear similar movements may be elicited by stroking the limb or tail base with a hair. The melanophore streak extends onto toes 4 and 5.
  
  
to IS a  
+
(Stage X) The margin of the foot paddle is indented between all five toes. The margin of the fifth web is directed toward the tip of the third toe. As toes 4 and 5 lengthen, the angle of the interdigital notch formed by the margin of the web becomes more acute. The half of the web adjacent to the fifth toe is referred to as the fifth toe web. If a line coinciding with its margin be extended, it will be seen to pass successively through the tips of toes 3, 2, and 1 and the prehallux.
 +
| [[File:Rugh_170.jpg|600px]]
 +
|}
  
 +
{|
 +
|
 +
===Stages in the metamorphosis of Rana pipiens===
 +
(Stage XI) The margin of the fifth toe is directed toward the tip of the second toe. The third toe usually has a melanophore streak.
  
 +
(Stage XII) The margin of the fifth toe is directed toward the tip of the first toe. Melanophores often appear on the second toe.
  
I II III IV V
+
(Stage XIII) The margin of the fifth toe is directed toward the tip of the prehallus.
  
Stages in the metamorphosis of Rana pipiens. (Stage I) The oral sucker elevations
+
(Stage XIV) Pigment-free patches appear on the metatarsophalangeal joints, where the proximal toe pads will develop later. About this time the brow-spot appears as a light spot on the mid-line slightly anterior to the level of the eyes. The nasolacrimal duct, developing as a cord of cells between the nostril and eye, is visible through the skin as a light line.
have completely disappeared. Four rows of labial teeth are present, one pre-oral and
 
three post-oral. Chromatophores have appeared and become numerous on the dorsal
 
and lateral surfaces, and extend progressively ventrad. The limb bud is visible as a  
 
faintly circumscribed elevation in the groove between the base of the tail and the belly
 
wall. The height of the elevation is less than half the diameter of the disk. {Stage H)
 
The height of the limb bud elevation (i.e., the length of the bud) is equal to half of
 
its diameter. The first row of post-oral labial teeth is usually at the middle to form a
 
pair of crescents. On the dorsal surface of the head the lateral line system is becoming
 
conspicuous as pigment-free lines, especially in darkly pigmented individuals. The
 
melanophore patches covering the gill region on either side usually meet in a narrow
 
band ventral to the heart. (Stage 111) The length of the limb bud is equal to its
 
diameter, and it continues to grow both in length and diameter at an approximately
 
equal rate. This stage is relatively long in duration. (Stage IV) The length of the limb
 
bud is equal to one and a half times its diameter. (Stage V) The length of the limb
 
bud is twice its diameter. The distal half of the bud is bent ventrad. There is no flattening of the tip. (Continued on facing page.)
 
  
 +
(Stage XV) The proximal toe pads appear.
  
 +
| [[File:Rugh_171.jpg|600px]]
 +
|}
  
Stage 23: 9 mm. total body length.
+
===Stages in the metamorphosis of Rana pipiens===
  
Mouth developing with embryonic teeth, opercular fold begins
+
[[File:Rugh_172.jpg|600px]]
backward growth, tongue anlage appears, carotid glands develop
 
from ventral wall of first branchial pouch, epithelioid bodies from
 
wall of second and third branchial pouches, oesophageal plug disappears, pancreas anlage is formed, pharyngeal arteries as well as subclavians grow from dorsal aorta, mesenteric and lumbar arteries appear, parachordal plate develops in floor of cranium, brain develops
 
anterior choroid plexus, optic lobes, and cerebellum, cranial nerves
 
(except abducens) well developed including all parts of trigeminal.  
 
  
Stage 24: 10 mm. total body length.
+
[[File:Rugh_173.jpg|600px]]
 
 
Atrophy of mucous glands, mouth with horny jaws and cornified
 
lips takes in vegetable diet, intestine long and looped, operculum
 
closed on right side, thyroid bifurcates and separates from pharynx,
 
spleen anlage appears, two or three branchial clefts break through,
 
mesonephros developing, utricle separated from saccule by oblique
 
partition, all semi-circular canals indicated, optic lobes formed, median cardinal vein appears, and posterior vena cava begins to develop.
 
 
 
Stage 25: 11 mm. total body length.
 
 
 
Cilia lost except on tail, operculum completed, cornification of
 
horny rasping papillae of jaws and lips, oesophagus differentiated
 
from stomach, lung buds invested with mesenchyme, pronephros
 
large and conspicuous, retina develops rods and cones, olfactory apparatus develops lateral appendix, internal choanae open, olfactory
 
nerve is derived from olfactory lobe neuroblasts, and abducens is
 
formed from neuroblasts of medulla.
 
 
 
12 mm. total body length stage:
 
 
 
Olfactory tube develops complete lumen from external nares to
 
internal choanae, thymus separates from dorsal part of first branchial
 
pouch and comes to lie posterior to tympanic membrane near mandibular muscles, maximum development of the pronephros which degenerates by 20 mm. stage, cortical (interrenal) adrenal arises from
 
peritoneum in vicinity of cardinal veins, paired gonad primordia
 
prominent.
 
 
 
 
 
 
 
15 mm. total body length stage:
 
 
 
Notochordal cartilage sheath develops, vertebrae begin to appear,
 
saccule gives rise to lagena (cochlea) and to a basilar chamber, sensory patches appear in ear epithelium, lateral line organ fully devel
 
oped, mesonephric tubules associated with median cardinal vein.
 
 
 
Metamorphosis at 75 to 90 days:
 
 
 
Loss of horny jaws, widening of mouth, shortening of gut and
 
changing of its histology to conform with a change from vegetable
 
diet to an omnivorous diet, loss of tail with its 32 pairs of spinal
 
nerves and development of two pairs of legs, shedding of larval skin,
 
disappearance of lateral line system as frog leaves aquatic environment, loss of caudal veins, full development of tongue, active functioning of endocrine glands (particularly thyroid and pituitary), and
 
appearance of differentiated gonads containing maturing gametes.  
 
  
 +
[[File:Rugh_174.jpg|600px]]
  
 +
The finished product of normal frog embryology.
  
The finished product of normal frog embryology.
 
  
 
{{Rugh1951 footer}}
 
{{Rugh1951 footer}}

Latest revision as of 12:45, 29 April 2013

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Rugh R. Book - The Frog Its Reproduction and Development. (1951) The Blakiston Company.

Frog Development (1951): Introduction | Rana pipiens | Reproductive System | Fertilization | Cleavage | Blastulation | Gastrulation | Neurulation | Early Embryo Changes | Later Embryo or Larva | Ectodermal Derivatives | Endodermal Derivatives | Mesodermal Derivatives | Summary of Organ Appearance | Glossary | Bibliography | Figures
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Appendix: Chronological Summary of Organ Anlagen Appearance of Rana pipiens

Stage 17: 3 mm total body length

Blastopore closes, neurenteric canal transient, neural tube closed but no differentiation of central nervous system, body elongated with back curve changing from convex to concave, myotomes evident but movement by surface ciliation. Internally most of major organ systems begin to appear including heart mesenchyme, visceral arches, and lateral plate mesoderm, pronephros, hypochordal rod, sense and gill plates, optic vesicles, and both auditory and olfactory placodes.

Stage 18: 4 mm total body length

First evidence of muscular movement, primary brain differentiations, infundibulum and hypophysis still separate, lateral line nerve develops from vagus placode, auditory placode becomes separated from head ectoderm, lens placode formed, ventral roots develop from spinal cord, hypochordal rod separated from gut, notochord becomes vacuolated and acquires an elastic and a fibrous coating from sclerotome, oesophageal plug formed, dorsal aorta paired anteriorly and single posteriorly, vitelline veins prominent and functional.

Stage 19: 5 mm total body length

Epiphysis well developed as evagination of prosencephalon, infundibulum, and hypophysis are approximated in position, thyroid evagination develops, trigeminal nerve from first cranial crest and placode, facial and auditory nerves from second cranial crest and placode, lens vesicle separated from head ectoderm, 45 pairs of somites developed (by 5.5 mm. stage), 32 of which are in tail, muscles with fibrillae, sclerotome abundant, heart differentiated and beating.

Rugh 167.jpg

Parts of the middle and inner ear of the frog. Schematized drawing.

Stage 20: 6 mm total body length

Hatches, oral suckers at maximum development, blood system well developed, including endocardium, myocardium, and pericardium of the heart, pulmonary veins develop but do not function, gill circulation abundant, blood islands numerous, lymph hearts first appear at level of somites III and IV, pronephros with glomi and segmental duct become partially embedded in posterior cardinal veins, a solid rod of ectoderm cells extend from olfactory pit to pharynx, four cranial ganglionic masses appear, optic nerve develops from neuroblasts of retina, and sympathetic nervous system arises from neural crests.

Stage 21: 7 mm total body length

Transition from larva to tadpole, mouth open, cornea transparent, cerebral hemispheres and vesicles differentiated, endolymphatic duct open to surface, heart folding upon itself, paired and metameric dorsal root ganglia, interatrial septum separates auricles, sex cell (genital) ridge appears.


Stage 22: 8 mm total body length

Heart partitions completed and heart differentiated, circulation reaches tail fin, lung buds develop, sub-notochordal rod disappears and mesonephros begins to form.


Rugh 168.jpg

Olfactory organs of Rana pipiens tadpoles at 20 mm total body length.

  • af - Anterior choanal fold
  • cc - Choanal canal
  • ct - Cornu trabeculae
  • cv - Christa ventralis
  • ec - Entrance canal
  • ig - Inferior canal
  • ir - Inferior recess
  • b - Lateral appendix
  • Ig - Lateral groove
  • pf - Posterior pharyngeal fold
  • pr - Posterior recess
  • sc - Superior cavity

Stage 23: 9 mm total body length

Mouth developing with embryonic teeth, opercular fold begins backward growth, tongue anlage appears, carotid glands develop from ventral wall of first branchial pouch, epithelioid bodies from wall of second and third branchial pouches, oesophageal plug disappears, pancreas anlage is formed, pharyngeal arteries as well as subclavians grow from dorsal aorta, mesenteric and lumbar arteries appear, parachordal plate develops in floor of cranium, brain develops anterior choroid plexus, optic lobes, and cerebellum, cranial nerves (except abducens) well developed including all parts of trigeminal.

Stage 24: 10 mm total body length

Atrophy of mucous glands, mouth with horny jaws and cornified lips takes in vegetable diet, intestine long and looped, operculum closed on right side, thyroid bifurcates and separates from pharynx, spleen anlage appears, two or three branchial clefts break through, mesonephros developing, utricle separated from saccule by oblique partition, all semi-circular canals indicated, optic lobes formed, median cardinal vein appears, and posterior vena cava begins to develop.

Stage 25: 11 mm total body length

Cilia lost except on tail, operculum completed, cornification of horny rasping papillae of jaws and lips, oesophagus differentiated from stomach, lung buds invested with mesenchyme, pronephros large and conspicuous, retina develops rods and cones, olfactory apparatus develops lateral appendix, internal choanae open, olfactory nerve is derived from olfactory lobe neuroblasts, and abducens is formed from neuroblasts of medulla.

12 mm total body length stage

Olfactory tube develops complete lumen from external nares to internal choanae, thymus separates from dorsal part of first branchial pouch and comes to lie posterior to tympanic membrane near mandibular muscles, maximum development of the pronephros which degenerates by 20 mm. stage, cortical (interrenal) adrenal arises from peritoneum in vicinity of cardinal veins, paired gonad primordia prominent.


15 mm total body length stage

Notochordal cartilage sheath develops, vertebrae begin to appear, saccule gives rise to lagena (cochlea) and to a basilar chamber, sensory patches appear in ear epithelium, lateral line organ fully developed, mesonephric tubules associated with median cardinal vein.

Metamorphosis at 75 to 90 days

Loss of horny jaws, widening of mouth, shortening of gut and changing of its histology to conform with a change from vegetable diet to an omnivorous diet, loss of tail with its 32 pairs of spinal nerves and development of two pairs of legs, shedding of larval skin, disappearance of lateral line system as frog leaves aquatic environment, loss of caudal veins, full development of tongue, active functioning of endocrine glands (particularly thyroid and pituitary), and appearance of differentiated gonads containing maturing gametes.

Stages in the metamorphosis of Rana pipiens

(Stage I) The oral sucker elevations have completely disappeared. Four rows of labial teeth are present, one pre-oral and three post-oral. Chromatophores have appeared and become numerous on the dorsal and lateral surfaces, and extend progressively ventrad. The limb bud is visible as a faintly circumscribed elevation in the groove between the base of the tail and the belly wall. The height of the elevation is less than half the diameter of the disk.


{Stage II) The height of the limb bud elevation (i.e., the length of the bud) is equal to half of its diameter. The first row of post-oral labial teeth is usually at the middle to form a pair of crescents. On the dorsal surface of the head the lateral line system is becoming conspicuous as pigment-free lines, especially in darkly pigmented individuals. The melanophore patches covering the gill region on either side usually meet in a narrow band ventral to the heart.


(Stage III) The length of the limb bud is equal to its diameter, and it continues to grow both in length and diameter at an approximately equal rate. This stage is relatively long in duration. (Stage IV) The length of the limb bud is equal to one and a half times its diameter.


(Stage V) The length of the limb bud is twice its diameter. The distal half of the bud is bent ventrad. There is no flattening of the tip. (Continued on facing page.)

Rugh 169.jpg

Stages in the metamorphosis of Rana pipiens

(Stage VI) The distal end of the limb bud is flattened mediolaterally to form the foot paddle. There are no interdigital indentations of the paddle margin.


(Stage VII) The fourth and fifth toe prominences are separated by a slight indentation of the margin of the foot paddle.


(Stage VIII) The margin of the foot paddle is indented between toes 5-4 and 4-3. The patch of melanophores on the limb lengthens into a streak extending from above the knee bend to foot.


(Stage IX) The margin of the foot paddle is indented between toes 5-4, 4-3, and 3-2. Usually spontaneous movements of the limb proper (flexion of the knee and ankle) can be seen under binocular microscopes. These movements may not appear until the following stage. Shortly after such movements appear similar movements may be elicited by stroking the limb or tail base with a hair. The melanophore streak extends onto toes 4 and 5.


(Stage X) The margin of the foot paddle is indented between all five toes. The margin of the fifth web is directed toward the tip of the third toe. As toes 4 and 5 lengthen, the angle of the interdigital notch formed by the margin of the web becomes more acute. The half of the web adjacent to the fifth toe is referred to as the fifth toe web. If a line coinciding with its margin be extended, it will be seen to pass successively through the tips of toes 3, 2, and 1 and the prehallux.

Rugh 170.jpg

Stages in the metamorphosis of Rana pipiens

(Stage XI) The margin of the fifth toe is directed toward the tip of the second toe. The third toe usually has a melanophore streak.

(Stage XII) The margin of the fifth toe is directed toward the tip of the first toe. Melanophores often appear on the second toe.

(Stage XIII) The margin of the fifth toe is directed toward the tip of the prehallus.

(Stage XIV) Pigment-free patches appear on the metatarsophalangeal joints, where the proximal toe pads will develop later. About this time the brow-spot appears as a light spot on the mid-line slightly anterior to the level of the eyes. The nasolacrimal duct, developing as a cord of cells between the nostril and eye, is visible through the skin as a light line.

(Stage XV) The proximal toe pads appear.

Rugh 171.jpg

Stages in the metamorphosis of Rana pipiens

Rugh 172.jpg

Rugh 173.jpg

Rugh 174.jpg

The finished product of normal frog embryology.


Historic Disclaimer - information about historic embryology pages 
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Pages where the terms "Historic Textbook" and "Historic Embryology" appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms and interpretations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)
Frog Development (1951): Introduction | Rana pipiens | Reproductive System | Fertilization | Cleavage | Blastulation | Gastrulation | Neurulation | Early Embryo Changes | Later Embryo or Larva | Ectodermal Derivatives | Endodermal Derivatives | Mesodermal Derivatives | Summary of Organ Appearance | Glossary | Bibliography | Figures

Reference

Rugh R. Book - The Frog Its Reproduction and Development. (1951) The Blakiston Company.


Cite this page: Hill, M.A. (2019, September 15) Embryology Book - The Frog Its Reproduction and Development 14. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Book_-_The_Frog_Its_Reproduction_and_Development_14

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© Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G