Intraovarian control of granulosa cell luteinization.

The entire ovarian follicle population is exposed to the same extraovarian hormonal environment, whereas only a select number of follicles ovulate. Local control of follicular maturation must, therefore, occur. Immature porcine granulosa cells will exhibit morphological and biochemical "luteinization" if cultured in the proper hormonal environment. This laboratory has investigated the role of follicular fluid factor in controlling this in vitro granulosa cell maturation. Follicular fluid from immature follicles inhibited LH hCG receptor induction and progesterone secretion in granulosa cell cultures. Fluid from mature follicles, however, exerted only a modest inhibition of LH hCG receptor induction and stimulated progesterone secretion. Estradiol-17 beta was inhibitory of progesterone secretion during early culture periods while stimulating LH hCG receptor induction. These studies demonstrate that follicular fluid environment may modulate granulosa cell maturation.