Uribe M C, Guillette L J
Laboratorio de Biología de la Reproducción Animal, Facultad de Ciencias, Universidad Nacional Autónoma de México, México.
J Morphol. 2000 Sep;245(3):225-40. doi: 10.1002/1097-4687(200009)245:3<225::AID-JMOR4>3.0.CO;2-M.
Although folliculogenesis and oogenesis have been observed in numerous reptiles, these phenomena have not been described in detail in a crocodilian. Oogenesis and histological features of the adult ovary of Alligator mississippiensis are described. Using a complex process, the ovary develops telolecithal oocytes that attain a diameter of 38.8 +/- 2.4 mm. The morphology of yolk platelets shows gradual changes throughout the oogenic process. Initially, yolk platelets are seen surrounded by a vesicle. As vitellogenesis advances, the vesicles contain numerous yolk spheres, with slowly growing platelets. The yolk spheres continue to increase in size and number within the vacuoles. Differences in the animal and vegetal poles are seen based on the morphology and size of the yolk platelets. The ovary of A. mississippiensis shows a well-developed system of lacunae and bundles of smooth muscle around the follicles in all stages of development. Several features seen in the ovary of A. mississippiensis are similar to those observed in birds. In particular, the morphology of the yolk platelets, especially during the middle and late vitellogenic stages, and the presence of a ovarian system of lacunae and smooth muscle. These similarities in the reproductive biology of crocodilians and birds contribute to current studies of the evolution of archosaurian reproduction.
尽管在许多爬行动物中都观察到了卵泡发生和卵子发生现象，但在鳄目动物中尚未对这些现象进行详细描述。本文描述了密西西比鳄成年卵巢的卵子发生和组织学特征。通过一个复杂的过程，卵巢发育出直径达38.8±2.4毫米的端黄卵母细胞。卵黄小板的形态在卵子发生过程中呈现出逐渐变化。最初，可见卵黄小板被一个囊泡包围。随着卵黄发生的推进，囊泡中含有大量卵黄球，卵黄小板缓慢生长。卵黄球在液泡内的大小和数量持续增加。根据卵黄小板的形态和大小，可以观察到动物极和植物极的差异。密西西比鳄的卵巢在发育的各个阶段都显示出围绕卵泡的腔隙系统和平滑肌束发育良好。密西西比鳄卵巢中观察到的几个特征与鸟类中观察到的特征相似。特别是卵黄小板的形态，尤其是在卵黄发生的中晚期，以及卵巢腔隙和平滑肌系统的存在。鳄目动物和鸟类生殖生物学的这些相似性有助于当前对主龙类生殖进化的研究。
