Levels of Follicle Regulatory Protein in Regular Menstruating and Amenorrheic Patients

Abstract

Many investigators have hypothesized that a timely induction or activation of the granulosal aromatase system and the concomitant changes in the intrafollicular sex steroid profiles are major determinants of the dominant follicle during its selection early in the ovarian cycle. Adashi and Hsueh (1982) suggested that intrafollicular estrogen can enhance the actions of FSH through aromatase stimulation. Once a chosen follicle is producing a significant amount of estrogen, it then would have the capacity to produce more estrogen than neighboring follicles and the selection of the dominant follicle would be assured. In contrast, follicles destined to undergo atresia may not be able to produce enough estrogen to counteract the adverse effects of FSH deprivation. Moor et al. (1978), Carson et al. (1981), and Tsonis et al. (1985) concluded that reduced aromatase activity in atretic follicles was due to a loss of existing aromatase activity rather than a failure to acquire this activity initially, and suggested that a decrease in aromatase activity was an early event in the atretic degeneration of antral follicles. It is the lack of granulosal aromatase and not androgen substrate per se which limits estrogen production in human atretic follicles. Thus, atresia appears to be, at least in part, an active event, mediated by the intra-ovarian suppression of FSH responsive aromatase activity.