Molecular determinants of sexual differentiation.

The processes of sexual differentiation have been greatly clarified by molecular biologic discoveries over the past five years. Gonadal differentiation into a testis or ovaries is controlled by a multitude of genes beginning with SRY which is believed to represent the testis determining factor. Other genes involved include SF-1, WT-1, DAX-1, and SOX9. The fully developed testis produces Mullerian inhibiting substance and testosterone to create the male phenotype; the female phenotype develops in their absence. This hormonally-driven process also requires additional factors and appropriate receptors. Errors in this pathway may be manifested clinically as intersex disorders, and the study of these disorders has helped to further elucidate the molecular mechanisms of sexual differentiation.