Ovarian follicle theca cells

Ovarian follicles, the basic unit of the ovary, consist of an outer layer of theca interna cells which encircle inner layers of granulosa cells. Granulosa cells, in turn, surround the innermost oocyte-cumulus complex. This complex array of cell layers is essential for the maturation and ovulation of the ovum. Significantly, the granulosa cell, by virtue of its close interaction with the outer theca and inner oocyte-cumulus compartment, serves to integrate information necessary for the achievement of successful follicular development. 

Fig. 1. Full-grown oocyte within its ovarian follicle. The follicle consists of the outer surface epithelium (SE), the middle theca (T), and the inner follicular epithelium, which, in this particular case, is represented almost entirely by the follicle cell nucleus (FCN). Macrovilli (MAV) from the follicle cell and microvilli (MIV) from the oocyte extend into the substance of the vitelline membrane (VM). Also shown are cortical granules (CG), yolk platelets (YP), pigment granules (PG), and lipid droplets (L). See Smith et al. (1968) for additional information.

Careful analysis of the biosynthetic properties of the membrana granulosa, the theca interna, and luteinized cells of the Graafian follicle and corpus luteum have revealed some of the factors determining the secretory products of these structures, but the role of the ovarian interstitial tissue is not completely established. There is much evidence suggesting that the latter tissue may secrete the major portion of ovarian androgens in women and in virilizing syndromes accompanying ovarian disease (Gil, L4, Mia, M5). 

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