Publication

Abstract : Gonochorism and hermaphroditism occur among teleost fishes and as in other vertebrates, sex is determined by monogenic, polygenic, and environmental means. There are at least 10 different master sex-determining genes discovered in teleosts. Regardless of the sexual system employed, once sex is determined, gonadal sex differentiation into ovaries and testes is relatively conserved. There is an antagonistic relationship between the testicular and ovarian pathways, which remains active throughout the lifetime to maintain the differentiated sexes. Estrogens play a pivotal role not only in initiating ovarian differentiation but also in maintaining the female phenotype in both gonochoristic and hermaphroditic fishes. This chapter reviews the current understanding of the diverse modes of sex determination, the relatively conserved process of gonadal sex differentiation and sexual plasticity in adulthood in teleosts.