Reproductive Biology and Embryology of the ... - Seaturtle.org
Reproductive Biology and Embryology of the ... - Seaturtle.org
Reproductive Biology and Embryology of the ... - Seaturtle.org
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
ORGANOGENESIS<br />
419<br />
sus, hyoglossus, <strong>and</strong> interm<strong>and</strong>ibularis, <strong>the</strong> dentary, splenial, <strong>and</strong> angular<br />
bones, Meckel's cartilages, lingual lipid, <strong>and</strong> fibrous tissue appear <strong>and</strong> are<br />
patterned comparable to those seen in vivo (Figs. 29A <strong>and</strong> B; Ferguson et<br />
al., 1982, 1983). However, anlagen for taste buds <strong>and</strong> teeth are absent. The<br />
differentiation <strong>of</strong> alligator branchial arches in vitro is superior to that for<br />
any o<strong>the</strong>r vertebrate studied to date, so that <strong>the</strong>y are useful models for<br />
investigation <strong>of</strong> a variety <strong>of</strong> developmental phenomena.<br />
B. Fses snd Noss<br />
There are accounts <strong>of</strong> <strong>the</strong> development <strong>of</strong> <strong>the</strong> face <strong>and</strong> nose for several<br />
genera: Alligator (Rathke, 1866; Clarke, 1891; Reese, 1901b, 1908, 1915a,<br />
1925; Bertau, 1935; Wettstein, 1954; Parsons, 1959a, 1970; Ferguson, 1981a,<br />
b, 1982b, 1984a), Caiman (Rathke, 1866; Parsons, 1970; Saint Girons, 1976),<br />
Melanosuchus (Bertau, 1935; Parsons, 1970) <strong>and</strong> Crocodylus (Rathke, 1866;<br />
Meek, 1893, 1911; Rose, 1893a, b; Seydel, 1896, 1899; Voeltzkow, 1899;<br />
Bertau, 1935; Wettstein, 1954; Wegner, 1957; Parsons, 1959a, b, 1970;<br />
Guibe, 1970m; Saint Girons, 1976; Bellairs, 1977; Ferguson, 1984a). That <strong>of</strong><br />
Cavialis is unknown except for a figure in Bruhl (1866), an illustration by<br />
Bustard (1980c) <strong>and</strong> a description <strong>of</strong> <strong>the</strong> nasal excrescence (Martin <strong>and</strong> A.<br />
d'A. Bellairs, 1977). Butler (1905) notes that <strong>the</strong> snout <strong>of</strong> ei<strong>the</strong>r Cavialis or<br />
Tomistoma is shorter <strong>and</strong> wider in <strong>the</strong> embryo than in <strong>the</strong> adult (but see<br />
(,<br />
Fig. 27. Alligator mississippiensis. Embryos. (A-D) <strong>and</strong> (F-G); Crocodylus lliloticus. (E-I). (A)<br />
Stage 7. Scanning electron micrograph (SEM) <strong>of</strong> <strong>the</strong> cranial aspect. Note <strong>the</strong> first <strong>and</strong> second<br />
branchial arches <strong>and</strong> first branchial cleft (arrowed). (B) Stage 8. Face-on view. Note <strong>the</strong><br />
midline fissure <strong>and</strong> facial processes. (C) Stage 9. Scanning electron micrograph. Note <strong>the</strong> four<br />
branchial arches, grooves <strong>and</strong> clefts, nasal pit, limb buds, <strong>and</strong> tail. (D) Higher power view <strong>of</strong><br />
C illustrating <strong>the</strong> true 1st <strong>and</strong> 3rd branchial arch clefts (arrowed), <strong>the</strong> four branchial arches<br />
<strong>and</strong> <strong>the</strong> branchial sinus. The apparent cleft between <strong>the</strong> 2nd <strong>and</strong> 3rd arches is an artifact. (E)<br />
Stage 10. Note <strong>the</strong> nasal pits <strong>and</strong> surrounding nasal processes, <strong>the</strong> lens <strong>and</strong> surrounding optic<br />
cup, <strong>the</strong> second branchial arch starting to overgrow arch 3, <strong>the</strong> 1st branchial cleft ventral to <strong>the</strong><br />
otocyst <strong>and</strong> <strong>the</strong> brain regions. (After Voeltzkow, 1899.) (F) Stage 14. SEM illustrating closure<br />
<strong>of</strong> <strong>the</strong> nasal pit slits by <strong>the</strong> medial nasal, lateral nasal <strong>and</strong> maxillary processes. Note <strong>the</strong><br />
intraoral bulges <strong>of</strong> <strong>the</strong> club shaped maxillary processes, signifying <strong>the</strong> onset <strong>of</strong> secondary<br />
palate development, <strong>the</strong> anterodorsal elevations <strong>of</strong> <strong>the</strong> medial nasal processes <strong>and</strong> <strong>the</strong> enlarging<br />
m<strong>and</strong>ible. Compare with Figure D. (G) Stage 9. Horizontal hematoxylin <strong>and</strong> eosin section<br />
through <strong>the</strong> five branchial arches (1-5). Note <strong>the</strong> thick endoderm, thinner ectoderm, branchial<br />
grooves <strong>and</strong> pouches, aortic arch arteries,<strong>and</strong> branchiomeric nerves. (H, I) Stages 12 <strong>and</strong><br />
15. Two diagrams illustrating <strong>the</strong> rearrangement <strong>of</strong> <strong>the</strong> first branchial cleft to form <strong>the</strong> external<br />
ear <strong>and</strong> superior ear flap. (After Voeltzkow, 1899.) A, Auricular hillocks; AA, aortic arch<br />
arteries; AD, anterodorsal elevations <strong>of</strong> nasal processes; BN, branchiomeric nerves; BP, branchial<br />
pouches; BS, branchial sinus; e, first branchial cleft; 0, denticles; E, eye; Ee, ectoderm;<br />
EN, endoderm; EX, external surface. F, ear flap; FL, fore limbbud; G, branchial grooves; H,<br />
hindbrain; HL, hind limbbud; LN, lateral nasal process; M, midbrain; MA, m<strong>and</strong>ibular process;<br />
MD, m<strong>and</strong>ible; MN, medial nasal process; MX, maxillary process; N, nasal placode; NP,<br />
nasal pit; 0, optic placode; Oe, optic cup; OT, otocyst; P, palatal shelves; PE, pericardial sac;<br />
PH, pharynx; 1, 2, 3, 4, branchial arches 1-4.