Implication of steroids in fish gonadal sex differentiation and sex inversion
Résumé
This paper reviews the current knowledge concerning the implication of steroid hormones in both gonadal sex differentiation in gonochoristic fish and gonadal sex inversion in hermaphroditic fish. Although steroids and steroidogenic enzymes are probably not the initial triggers of gonadal sex differentiation or gonadal sex-inversion, new data, including molecular approaches, confirm that they are key physiological steps in the regulation of these processes. The importance of estrogens in fish gonadal differentiation is now more and more documented, and aromatase is probably one of the key enzymes needed for both ovarian differentiation in gonochoristic fish and for sex inversion in hermaphroditic fish. However, the implication of 11-oxygenated androgens in fish sex differentiation or sex inversion also deserve attention and we hypothesise that the balance between gonadal 11-oxygenated androgens and estrogens would directed either male (excess of androgens) or female (excess of estrogens) gonadal sex differentiation.