CONICET | Buscador de Institutos y Recursos Humanos

Inthis study we provide a morphological description of Caiman latirostris phallus duringtheir early ontogenesis. Caiman eggs were incubated at 33°C (male producingtemperature), and samples were obtained at stages 24 and 26 (after the thermo-sensitiveperiod) of embryonic development, at hatching time (or stage 28), and 24 monthsafter hatching (juvenile). During the periods mentioned above, the phallus hadan oval shape with a ventral and dorsal surface and two lateral edges; and a phallicsulcus running along its dorsal surface. In the gross anatomy two segments wererecognized: the shaft and the glans (distalexpansion like cuff). At stage 24, the sulcus was a stratified epithelium,flanked by irregular shaped cells and a profuse fundamental substance. Betweenstages 26 and 28, a ring of vascular elements distinguished the anlage of thecorpora cavernosa from the corpus spongiosum; this latter immediately borderingthe phallic sulcus. The corpora exhibited a network of collagen fibers looselyorganized. Smooth muscle cells weredifferentiated adjacent to the phallic sulcus on the dorsal surface of thecorpus spongiosum. Nerveswere developing accompanying the anlage corpora organization. By juvenileperiod, the sulcus in the deep lumen was stratified ciliated epithelium withmucin cells different from earlier stages. The corpora cavernosa had turnedinto corpora fibrosa with smooth muscle bundles mixed among rich tissuecollagen fibers. The muscle bundles in the corpora cavernosa had formed twoorientations, radially (deeply) and longitudinally (superficial)-orientated,while in the corpus spongiosum the muscle was longitudinally-orientated alignedwith the sulcus. The glans contained a lacunar connective tissue, with largeand irregular vascular spaces. Our analysis of caiman phallus development afterthe thermo-sensitive period, suggests that the glans development and theepithelium sulcus specializations are post-hatching process.