The role of H-Y antigen in gonadal differentiation and anomalous sexual development

Abstract

Gonadal differentiation involves the organization of indifferent gonads containing primordial germ cells into either seminiferous tubules or primary follicles. This process, which in the human becomes evident in the 7th week of gestation, appears to be determined by the presence or absence of a Y chromosome. The indifferent gonad differentiates into a testis in the presence of a Y chromosome and into an ovary if a Y chromosome is lacking. The number of X-chromosomes is irrelevant to testicular or ovarian differentiation, although it does affect the later maturation and function of the gonads. The genes on the Y chromosome exert their influence on gonadal differentiation through the intermediary of a male determining factor which has now been identified as the H- Y antigen. The correlation between gonadal development and the presence of a Y chromosome has exceptions, examples of which are 46 XX males and 46 XY females. Testicular differentiation appears to correlate better with the presence of H- Y antigen. This paper reviews the H- Y antigen in various anomalies of sexual development and the light it has shed on the mechanism of gonadal differentiation.