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  • Life and Medical Sciences  (6)
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  • 1
    Electronic Resource
    Electronic Resource
    Porosity of eggshells from wild and captive, pen-reared alligators (Alligator mississippiensis) (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 203 (1990), S. 35-39 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Artificially incubated fertile eggs from wild alligators have a significantly better hatch rate than those of captive, pen-reared alligators, possibly due to differences in the morphology of the eggshells. We compared the morphology of eggshells of wild alligators to those of captive alligators living in semi-natural environmental pens. Lengths and widths of eggs were measured and volume was determined, assuming an ellipsoid shape. Eggs were also evaluated for the quality of the eggshell (the presence or absence of rough deposits). Pieces of shell were cut from unincubated eggs and from eggs incubated for 55 days (just before hatching) and examined by scanning electron microscopy. Open pores on the outer surface of the shells were counted and thickness of the pieces was measured from micrographs. Results indicated that the number of pores on eggshells was lowest in eggs of captive alligators with early embryonic death. The number of pores was intermediate in eggs with early embryonic death from wild alligators, and the number of pores was highest in eggs with full-term embryos from wild or captive alligators. It is suggested that decreased porosity of eggshells may be associated with early embryonic death, is more prevalent in captive animals, and may, therefore, be related to poor hatch rate among penreared alligators.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052030105
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  • 2
    Electronic Resource
    Electronic Resource
    Neural elements in the cruciate ligaments and menisci of the knee joint of the American alligator, Alligator mississippiensis (1989)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 202 (1989), S. 165-172 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Knee joints from adult, juvenile, hatchling, and embryonic (full term) American alligators were dissected to reveal the cruciate ligaments and the medial and lateral menisci. Two anterior cruciate (major and minor), a posterior cruciate, an intermeniscal, and a meniscofemoral ligament were identified. In addition, we found a fourth internal ligament which has not been reported previously. Menisci and ligaments from left knees were fixed in formalin and processed for routine histological observation. Those from right knees were stained in bulk by using a gold chloride method and were either frozen and sectioned at 100 m̈m on a sliding microtome or were processed for paraffin sections at 30 m̈m. The morphology of the collagenous, cartilaginous, and vascular constituents of the tissues was similar to that of the dog, cat, and human. Nerve fibers were observed in all tissues sampled. Structures resembling Golgi tendon organs and Pacinian corpuscles were identified, reinforcing the theory that neural elements within cruciate ligaments and menisci may provide afferent input that affects the function of the knee joint.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052020204
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  • 3
    Electronic Resource
    Electronic Resource
    Changes in femoral morphology during egg-laying in Alligator mississippiensis (1986)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 189 (1986), S. 183-188 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Birds and many reptiles are egg-layers. Birds provide calcium for the formation of eggshells by resorbing medullary bone, which is laid down before ovulation. Turtles do not possess this mechanism and resorb structural bone to form eggshells. Femora from three groups of alligators (egg-laying females; quiescent, immature, or barren females; and males) were examined to determine if alligators, which are closely related to birds in evolution, resorb structural bone during the formation of eggshells as do turtles. Microradiographs of cross sections from femoral mid-shafts were analyzed for porosity, and the robusticity index of each femur was determined. Scanning electron micrographs of anorganic endosteal and periosteal femoral surfaces were analyzed to determine numbers of entrances of vascular canals, numbers of lacunae of osteoblasts, and types of femoral surfaces. Femora from egg-laying females were significantly less robust than those of other females or males, and sections of bone from the egg-layers were significantly more porous than those of the other groups. Scanning electron microscopy of anorganic femoral endosteal surfaces from egg-laying females revealed significantly more resorption areas when compared with males or non egg-laying females. Periosteal surfaces from egg-layers had significantly more resting and less bone-forming surface than those from the other groups. Results indicated that apposition of periosteal bone may have been reduced in egg-layers and that egg-laying alligators, like turtles, resorb endosteal structural bone, which may be used as a source of calcium for the formation of eggshells.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051890208
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  • 4
    Electronic Resource
    Electronic Resource
    Morphology of shells from viable and nonviable eggs of the chinese alligator (Alligator sinensis) (1994)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 222 (1994), S. 103-110 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphology of eggshells from hatched eggs of captive Chinese alligators (Alligator sinensis) was compared with that of shells from eggs with early embryonic death and with the morphology of eggshells from the American alligator (Alligator mississipiensisis). Pieces of shells were examined in the scanning electron microscope. Parameters examined included: numbers of open pores on the outer surfaces, total shell thickness, and thickness of the outer densely calcified and inner mammillary layers. Results indicate that shells from Chinese and American alligator eggs with early embryonic death have a thicker outer densely calcified layer than do shells from hatched eggs or full-term embryos. Also, eggshells from Chinese alligator eggs with dead embryos have fewer open pores on the outer surface than do shells from hatched eggs, as has been reported earlier for the American alligator (Wink et al., '90). © 1994 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052220110
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  • 5
    Electronic Resource
    Electronic Resource
    Changes in femoral robusticity and porosity during the reproductive cycle of the female alligator (Alligator mississippiensis) (1987)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 193 (1987), S. 317-321 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: To help understand the nature of skeletal changes during the reproductive cycle of the female alligator, we compared femoral robusticity (density) and porosity of cross-sections from the midshafts of femora from the following groups of female alligators: (1) immature; (2) pre-ovulatory; (3) postovulatory with soft-shelled oviducal eggs; (4) post-ovulatory with hard-shelled oviducal eggs; (5) post-ovulatory with eggs in the nest; (6) post-ovulatory with hatched eggs; and (7) mature, quiescent. Femora from alligators with eggs in the nest were significantly less robust (dense) than those of the other groups except those with hard-shelled oviducal eggs. Cross sections from the midshaft of femora from alligators with eggs in the nest were significantly more porous than those from all the other groups. The results indicated that calcium was mobilized from the femoral shaft shortly before eggs were laid and that femoral density returned to normal levels for mature alligators 1-2 months after egg-laying.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051930309
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  • 6
    Electronic Resource
    Electronic Resource
    The relationship of pores and mammillae on the inner surface of the eggshell of the alligator (Alligator mississippiensis) (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 204 (1990), S. 227-233 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphology of the eggshell of the alligator, Alligator mississippiensis, is similar to that of birds. In many avian species there is a positive linear correlation between the numbers of pores and mammillae on the inner surfaces of eggshells, indicating that the distribution and density of mammillae may determine the porosity of the shell. It is not known, however, if a relationship exists between pores and mammillae on the shell of the alligator. Using a scanning electron microscope, we counted pores and mammillae on the inner surfaces of pieces of shell from the middle of fertile and infertile eggs from wild and captive, pen-reared alligators. Data were analyzed by ANOVA, Duncan's multiple range tests and linear regression equations. Results demonstrate a positive linear correlation between the numbers of pores and mammillae on the shells of unincubated fertile and infertile eggs from wild and captive alligators; however, there is no correlation between pores and mammillae on shells of eggs that were incubated for 55 days. It is suggested that initially the porosity of the eggshell of the alligator is related to the density of mammillae on the inner surface of the shell and that erosion of the shell during incubation destroys the original relationship between pores and mammillae.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052040210
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