H-Y binding in the gonad: inhibition by a supernatant of the fetal ovary.

H-Y antigen, the product of mammalian testis-determining genes, is released in the free state by testicular cells. Molecules of free H-Y antigen are bound in vitro by dispersed cells of the adult ovary. The binding reaction is inhibited by specific H-Y antibody. It is also inhibited by a diffusible factor of the newly differentiated fetal ovary. These observations favor the view that testicular organogenesis depend upon dissemination and binding of H-Y molecules by cells of the undifferentiated gonad (XY or XX, both having H-Y receptors), and raise the question of whether ovarian organogenesis may be promoted by a "female" molecule corresponding to H-Y of the male.