Desenvolvimento embrionário e diferenciação gonadal de Podocnemis unifilis (Testudines: Podocnemididae) em temperatura controlada

Abstract

This work aimed to describe the external morphological characters and gonadal differentiation during the embryonic development of Podocnemis unifilis at controlled temperature. 100 eggs were collected and incubated in an artificial incubator. The incubation period was 60 days, with an average incubation temperature of 31.8ºC. Macroscopic analyzes, light microscopy and transmission electron microscopy were performed. The main characteristics used to describe and compare embryonic development were: head, mandibular process, eyes, limbs, carapace and plastron. In gonadal development, primordial germ cells (CGPs) were only visualized from the 7th day of incubation, and were located in the posterior region of the embryo's body and between the 9th and 11th incubation it was possible to observe the migration of the CGPs from the yolk sac towards the ventromedial region of the primitive mesonephral wall. At 20 days of development, the undifferentiated gonad is established and two distinct regions are identified, the external cortical region characterized by the presence of CGPs, and the internal medullary region where the primitive sexual cords were present. The gonadal differentiation started after 35 days of incubation observing the beginning of the organization of the sexual cords for the formation of the seminiferous tubules. All the gonads analyzed in this study differed, forming testicles. Morphological studies of embryonic development and gonadal characterization generate information about the reproductive biology of species, and this information helps in research to develop management strategies and / or making existing methods more efficient.