Morphogenesis and patterning of the phallus and cloaca in the American alligator, alligator mississippiensis.
Morphogenesis and patterning of the phallus and cloaca in the American alligator, alligator mississippiensis.
复制标题
美洲短吻鳄密西西比短吻鳄阴茎和泄殖腔的形态发生和模式。
DOI：
10.1159/000364817
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Cohn,MartinJ
中科院分区：
文献类型：
--
作者：
Gredler,MarissaL;Seifert,AshleyW;Cohn,MartinJ
In most animals, reproduction by internal fertilization is facilitated by an intromittent organ, such as the penis in amniote vertebrates. Recent progress has begun to uncover the mechanisms of mammalian external genital development; however, comparatively little is known about the development of the reptilian penis and clitoris. Here, we describe the development of the phallus and cloaca in the American alligator, Alligator mississippiensis. The embryonic precursor of the penis and clitoris is the genital tubercle, which forms by the budding of genital mesenchyme beneath the ventral body wall ectoderm, adjacent to the cloacal membrane. The cloacal lips develop from another pair of outgrowths, the lateral swellings. Early development of the alligator phallus, cloaca, and urogenital ducts generally resembles that of other reptiles, suggesting that differences in adult reptilian phallus and cloacal anatomy arise at later stages. The phallic sulcus is derived from the cloacal endoderm, indicating that the crocodilian sulcus is functionally and developmentally homologous to the mammalian urethra. Initial external genital outgrowth and patterning occur prior to temperature-dependent sex determination. Our analysis of alligator phallus and cloaca development suggests that modifications of an ancestral program of urogenital development could have generated the morphological diversity found in the external genitalia of modern amniotes.
