The effect of epidermal growth factor in human granulosa cells varies with follicle size.

EGF decreases aromatase activity and stimulates the proliferation of granulosa cells. To determine if EGF affects follicles of different maturity differently, human granulosa cells obtained from 6 patients at the time of IVF were pooled according to size and cultured in serum free medium with or without EGF. Estrogen production at 72 h was determined by measuring tritiated water formed in a 1-h culture with 1 beta [3H] androstenedione. The change in estrogen production with EGF was compared for cells from the smallest and largest follicles for each patient. Estrogen production in response to EGF decreased with increasing follicular size in all six observations. EGF may mediate luteinized granulosa cell aromatase activity in vivo, and may be a factor responsible for the relative decline in estrogen production in the preovulatory follicle.