Oestrogens and temperature-dependent sex determination in reptiles: all is in the gonads.

In many species of oviparous reptiles, the first steps of gonadal sex differentiation depend on the incubation temperature of the eggs. Feminization of gonads by exogenous oestrogens at a male-producing temperature and masculinization of gonads by antioestrogens and aromatase inhibitors at a female-producing temperature have irrefutably demonstrated the involvement of oestrogens in ovarian differentiation. Nevertheless, several studies performed on the entire gonad/adrenal/mesonephros complex failed to find differences between male- and female-producing temperatures in oestrogen content, aromatase activity and aromatase gene expression during the thermosensitive period for sex determination.

Lymphoid aggregates in gonads of embryos, hatchlings, and young of turtles with temperature-dependent sex determination.

Cellular infiltrations forming lymphoid-like aggregates were previously observed in gonads of two turtle species exhibiting temperature-dependent sex determination (TSD): at hatching in Chelydra serpentina; at and after hatching in Emys orbicularis. We show here that such aggregates are also present in gonads of Testudo graeca by the end of embryonic development, suggesting that their occurrence is general in turtles. Since in C.

Degree of sex reversal as related to plasma steroid levels in genetic female chickens (Gallus domesticus) treated with Fadrozole.

The objectives of this work were to determine whether or not plasma levels of testosterone and estradiol reflect the various grades of sex reversal in genetic female chickens treated with Fadrozole (CGS 16949 A), a nonsteroidal aromatase inhibitor, and whether gonadal aromatase activity and plasma levels of testosterone and estradiol in treated females can or not be modified by post-hatch treatments with Fadrozole or Fadrozole + testosterone. Eggs were injected with 1 mg Fadrozole on day 4 of incubation. In females having developed sex-reversed gonads, endocrine parameters (estradiol and testosterone) at and after 13 weeks of age were indicative of the degree of sex reversal, with, for example, sex-reversed females with two testes having the highest levels of testosterone and the lowest levels of estradiol.

Sex reversal and aromatase in chicken.

Aromatase inhibitors administered before sexual differentiation of the gonads can induce sex reversal in female chickens. To analyze the process of sex reversal, we have followed for several months the changes induced by Fadrozole, a nonsteroidal aromatase inhibitor, in gonadal aromatase activity and in morphology and structure of the female genital system. Fadrozole was injected into eggs on day four of incubation, and its effects were examined during the embryonic development and for eight months after hatching.

Expression of AMH, SF1, and SOX9 in gonads of genetic female chickens during sex reversal induced by an aromatase inhibitor.

Aromatase inhibitors administered prior to histological signs of gonadal sex differentiation can induce sex reversal of genetic female chickens. Under the effects of Fadrozole (CGS 16949A), a nonsteroidal aromatase inhibitor, the right gonad generally becomes a testis, and the left gonad a testis or an ovotestis. We have compared the expression pattern of the genes encoding AMH (the anti-Müllerian hormone), SF1 (steroidogenic factor 1), and SOX9 (a transcription factor related to SRY) in these sex-reversed gonads with that in control testes and ovaries, using in situ hybridization with riboprobes on gonadal sections.