Reproductive Biology and Embryology of the ... - Seaturtle.org
Reproductive Biology and Embryology of the ... - Seaturtle.org
Reproductive Biology and Embryology of the ... - Seaturtle.org
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INTRODUCTION<br />
331<br />
I. INTROOUCTION<br />
II.<br />
REPRODUCTIVE BIOLOGY<br />
A. General, 333<br />
B.<br />
C.<br />
CONTENTS<br />
Sexual Maturity <strong>and</strong> Adult Sex Ratios, 333<br />
Courtship, Spermatogenesis, Ovulation, Copulation,<br />
<strong>the</strong> Breeding Season, Fertilization, <strong>and</strong> Egg Laying, 336<br />
D. Nesting <strong>Biology</strong>, 349<br />
E. Maternal Behavior, 355<br />
F.<br />
Captive Breeding, Egg Collection, <strong>and</strong> Artificial<br />
Incubation, 356<br />
G. Hatching, 360<br />
331<br />
333<br />
P. Endocrine Gl<strong>and</strong>s, 445<br />
Q. Thymus <strong>and</strong> Immune System, 446<br />
R, Limbs <strong>and</strong> Tail, 446<br />
S, Integument <strong>and</strong> Its Gl<strong>and</strong>s, 450<br />
T. Caruncle, 450<br />
VIII. DEVELOPMENTAL ABNORMALITIES<br />
451<br />
IX. SHELL·LESS, SEMI.SHELL.LESS, AND IN VITRO<br />
CULTURE TECHNIGUES 460<br />
X. CONCLUSIONS 462<br />
REFERENCES 464<br />
III.<br />
THE EGGSHELL AND SHELL MEMBRANES<br />
A. General, 363<br />
363<br />
B. Egg B<strong>and</strong>ing, 363<br />
C. Structure, 367<br />
D. Chemical Composition, 374<br />
E.<br />
Water <strong>and</strong> Gas Conductance <strong>and</strong> Embryonic<br />
Metabolism, 376<br />
I. INTRODUCTION<br />
IV.<br />
V.<br />
VI.<br />
VII.<br />
THE EGG CONTENTS AND EXTRA.EMBRYONIC<br />
MEMBRANES<br />
EARLY EMBRYONIC DEVELOPMENT [BEFORE EGG<br />
LAYING)<br />
STAGES OF EMBRYONIC DEVELOPMENT [AFTER EGG<br />
LAYING)<br />
ORGANOGENESIS<br />
A. Branchial Arches, 41 6<br />
B. Face <strong>and</strong> Nose, 41 9<br />
C.<br />
Palate <strong>and</strong> Nasopharyngeal Duct, 421<br />
D. Tongue, 427<br />
E. Ear, 428<br />
F. Eye, 428<br />
G.<br />
Chondrocranium <strong>and</strong> Osteocranium, 431<br />
H. Teeth, 431<br />
I. Central Nervous System, 432<br />
..J. Vertebrae <strong>and</strong> Ribs, 435<br />
K. Respiratory System, 436<br />
L. Cardiovascular System, 436<br />
M. Diaphragm, 438<br />
N. Gastrointestinal System, 438<br />
O.<br />
Urogenital System <strong>and</strong> Sex Determination, 440<br />
377<br />
381<br />
390<br />
416<br />
I"<br />
t<br />
I'<br />
The living crocodilians, represented by 26 living species placed in three<br />
subfamilies (see Table III later in chapter), are <strong>the</strong> end products <strong>of</strong> a relatively<br />
conservative lineage, which arose from <strong>the</strong>codont ancestors approximately<br />
230 million years ago (Carroll, 1969; Walker, 1972). The evolution<br />
<strong>and</strong> taxonomy <strong>of</strong> <strong>the</strong> order have been <strong>the</strong> subject <strong>of</strong> considerable debate<br />
involving paleontological (Steel, 1973), neontological (Wermuth <strong>and</strong> Mertens,<br />
1977; Groombridge, 1982), immunological, <strong>and</strong> biochemical approaches<br />
(Perutz et al., 1981; Le Clercq et al., 1981; Densmore, 1981; Coulson<br />
<strong>and</strong> Hern<strong>and</strong>ez, 1983). Densmore's <strong>and</strong> Groombridge's classifications<br />
are used here. All types <strong>of</strong> data indicate that birds are <strong>the</strong> closest living<br />
relatives <strong>of</strong> crocodilians. However, several aspects <strong>of</strong> crocodilian embryogenesis,<br />
for example, palatogenesis (Section VII, VIII), resemble mammalian<br />
phenomena, <strong>and</strong> variations in hemoglobin amino acid sequences place<br />
crocodilians closer to mammals than to snakes (Perutz et al., 1981; Le<br />
Clercq et al., 1981; Densmore, 1981). Thus, fur<strong>the</strong>r studies <strong>of</strong> crocodilian<br />
embryogenesis not only may shed light on fundamental aspects <strong>of</strong> <strong>org</strong>anogenesis,<br />
but also exploit <strong>the</strong> potential <strong>of</strong> <strong>the</strong>se vertebrates as models<br />
for experimental investigations, which are difficult or impossible to perform<br />
in o<strong>the</strong>r amniotes (Ferguson, 1981a, b, 1984a).<br />
Crocodilian embryology has received very little attention. Some general<br />
accounts are available for Crocodylus niloticus (Rathke, 1866; Voeltzkow,<br />
1899, 1901, 1903a), Alligator mississippiensis (Clarke, 1891; Reese, 1908,<br />
1910a-c, 1912, 1915a, b, 1921, 1936), C. palustris, <strong>and</strong> C. porosus (Derani<br />
330