GONADOGENESIS IN CAIMAN LATIROSTRIS

IUNGMAN, J.; MARTINEZ, V.H.; PIÑA, C.I.

Manaos

Congreso; 20th Working Meeting of the Crocodile Specialista Group (CSG/SSC/IUCN); 2010

CSG/SSC/UICN

The sex of Broad-Snouted Caiman embryos is mediated by incubation temperature within a critical period. We described gonad histology when differentiation sex occurs, in order to identify sex-dependents events. Consequently, we set embryos incubated at specific sex-determine temperatures: at 31 °C (100 % female) and 33 °C (100 % males); and hatchlings coming from these temperatures. Up to 18 stage of development the caiman gonads at both temperatures comprise an outer epithelium containing germ cells; and underlying medullar cords. Signs of testis differentiation at 33 °C are first detected at the stage 19, when germ cells in association with somatic cells begin to migrate towards medullar cords. During stage 22, seminiferous cords become apparent and myoid cells are identified. At stage 24 lengthened cords enclose germ and somatic (“Sertoli”) cells, but interstitial tissue is scarce. At 31 °C, ovary differentiations is characterized by an increase of cortical germs cells from stage 19, and a subsequent proliferation of primary oocytes which are clearly identifiable at stage 22. At hatching, males exhibit testes with distinct interstitial tissue which have Leydig cell clusters; and seminiferous tubules containing single cell Sertoli and spermatogonia on the basement membrane. Female show an ovarian cortex formed by oogonia-oocyte nests, and oocytes at different folliculogenesis stages. No regression is found an ovarian medulla, though it is populated by sporadic lacunae. Although gonadal sex has been well established at hatching, the final gonad structure will be completed during post-hatch development