Intragonadal regulation of male and female reproduction

FSH and LH are vital endocrine regulators of gonadal growth and function. H owever, locally produced - paracrine - steroidal and nonsteroidal substance s mediate and modulate gonadotrophin action on gonadal cells. The testis an d ovary share obvious morphological and functional homologies. Optimal func tioning of the spermatogenic (Sertoli cells) and follicular (granulosa cell s) epithelia depends on both endocrine stimulation by FSK and paracrine sti mulation by androgen. In each gland, inhibins and related factors produced by FSH-stimulated Sertoli (testis) cells or granulosa (ovary) cells recipro cally modulate LH-stimulated androgen synthesis in neighbouring Leydig (tes tis) or thecal (ovary) cells. Thus androgens and inhibins are << unisex >> paracrine regulators that operate in similar ways in both ovary and testis.