Figure 1. A, Formation of the urogenital ridge in the embryo. The development of the intermediate mesoderm into the urogenital ridge during the embryonic period sets the stage for later differentiation into the gonads, Wolffian and Müllerian ducts. Under the control of several sex-independent genes, the ridge takes shape awaiting the sex-dependent signals that will evoke gonadal identity and the subsequent reproductive duct growth. B, Gonadogenesis and reproductive duct development. Later in embryonic development at least six gonad-determining genes (SF-1, Lim 1, WT-1, GATA-4, Lhx 9, and Emx2) direct formation of the indifferent gonads from the intermediate mesoderm. Absence of any of these genes blocks gonadal development. Thereafter, in males the genes necessary for normal testes, Sry, SF-1, Sox-9, and Dhh act to produce the gonad. The secretion of testosterone and MIS ensure the development of the normal male phenotype. In females, on the other hand, the lack of male determining genes allows for the development of ovaries. Wnt-4, Fa, and several of the Hoxa genes promote the proper growth and development of the Fallopian tubes, uterus, cervix, and vagina.
Source: Endocrinology 2001 Jun;142(6):2167-72
Edited by Aldo Campana,