Abstract Sex steroid hormones are critical in gonadal differentiation in turtles. The gonads are not the only organs responsible for producing these hormones during this phase. Mesonephros play an important role in steroidogenesis. The present study aimed to investigate the presence of steroidogenic cells in mesonephros of Podocnemis expansa during gonadal differentiation and to evaluate their morphology and ultrastructure. Ten embryos of P. expansa were collected from 5 nests on day 36 of incubation, during spawning period on an artificial beach. Embryos were extracted from eggs by slicing the shell and euthanized. They were dissected under a stereoscopic microscope to collect the gonad-mesonephro complex, in which were fixed and subsequently processed for light microscopy, immunohistochemistry and transmission electron microscopy analysis. During histological analysis was observed mesonephros has typical morphological structure. Immunohistochemistry showed immunoreaction to aromatase in cells of intertubular space. Confirming these findings, it was possible to observe a type of intertubular cell in several regions of mesonephro, being more predominant in region close to blood vessels, distal and proximal tubules. In ultrastructural analysis these cells were characterized by having a clear, large, and rounded nucleus with evident nucleolus and cytoplasm rich in electron-dense droplets. This study demonstrated for the first time the presence of cells with morphological, immunohistochemical and ultrastructural characteristics similar to steroid-producing cells in P. expansa mesonephrons, suggesting that this organ may contribute to gonadal differentiation in this species.

Abstract Domestic and wild goats are very susceptible animals to predation, specially when pregnancy occurs. This study aimed to evaluate the use of goat fetal ovarian tissue for vitrification followed by xenotransplantation and fresh xenotransplantation in two immunosuppressed mice models (C57BL/6 SCID and Balb-C NUDE). Goat fetus ovaries were collected in slaughterhouses, divided into small cortical pieces and were destined for fresh xenotransplantation (FX) and cryopreservation followed by xenotransplantation (CX). Five recipients from each lineage were used for FX and 10 animals from each lineage for CX. The mice were euthanized after 65 postoperative days, and the transplants were collected for microscopic assessment. The blood plasma was collected for estradiol measurement. Independently of mice strain, all recipients presented complete estrus cycle in FX and 80% after CX groups. Follicles were observed at all development stages without morphological changes. The volume density and total vessel surface observed in the transplants were different (p <0.01) between groups. The estradiol levels in the recipients did not differ (p <0.05) among the treatments. Thus, it is possible to activate the preantral follicles in the ovaries of fetuses by optimizing germplasm utilization and conservation of domestic and endangered wild goats that are in predatory situations, undesirable drowning or accidental death, since provided conditions for xenotransplantation are performed.