Mesenchymal-epithelial cell interactions in the ovary: estrogen-induced theca cell steroidogenesis.

The role of mesenchymal-epithelial cell interactions in the control of ovarian physiology was investigated Theca cells are the mesenchymal (i.e. stromal) like cells that surround the ovarian follicle and produce androgen in response to the gonadotropin luteinizing hormone (LH). Granulosa cells are the epithelial-like cells that form the follicle, support the developing oocyte, and utilize androgens produced by theca cells as a substrate for the production of estrogen Observations presented indicate that estrogen produced by granulosa cells dramatically stimulates androgen production by theca cells Estrogen was found to have greater stimulatory effect on theca cell androgen production than gonadotropin, and a combination of estrogen and gonadotropin results in a greater than additive response of the two hormones. Regulation of androgen production by estrogen provides a local feedback loop in the follicle that will significantly influence ovarian steroidogenesis. This steroid-mediated theca-granulosa cell interaction provides evidence for the importance of mesenchymal (i.e. stromal)-epithelial cell interactions in adult tissues and implies that epithelial cells can produce paracrine factors that modulate mesenchymal cell function and differentiation. The theca cell-granulosa cell interaction identified is postulated to be a critical mesenchymal-epithelial cell interaction for the control of ovarian physiology and the endocrine status of the female.