Estrogen biosynthesis in the ovaries and testes.

This review has presented some of our recent data on estrogen biosynthesis and has drawn upon these, as well as numerous observations, to design the two-cell type, two-gonadotropin model, applicable to both sexes, for the biosynthesis of gonadal estrogens and its regulation. Some of the data upon which this model, depicted in Figure 15, are based are quite preliminary and in many cases have been derived from experiments with tissues from animals over a rather narrow age span. Consequently, in future years this model may appear too simplistic to explain gonadal estrogen synthesis at all stages of development. However, whatever the fate of the model, whether it be broken and rebuilt on firmer foundations or furnished more lavishly, it is hoped that it will result in some of the corners being "rounded." There has been an emphasis on some of the similarities between the two sexes with respect to enzyme capacities, hormone receptors, and control mechanisms for the various cell types in the ovaries as compared to the testes. In particular, the striking similarities both structurally and functionally between Sertoli cells and granulosa cells are now recognized. Vive la difference.