Sexual differentiation of the gonads and of the reproductive tract.

Between 1947 and 1952 Alfred Jost deduced that sexual differentiation is an ordered process in which chromosomal sex determines gonadal sex and gonadal sex in turn directs the development of phenotypic sex. This powerful formulation has been substantiated by both genetic and endocrine evidence and has had a profound impact on clinical medicine as well as on biology. The means are now at hand for dissecting the molecular mechanisms by which genetic determinants and regulatory factors interact in this cascade to produce the male and female phenotypes.