The cellular activity of different sized follicles in cycles treated with gonadotrophin-releasing hormone analogue.

The activity of granulosa cells derived from different sized follicles surrounding oocytes of apparently comparable maturity was evaluated in hyperstimulated ovaries. Granulosa cells were obtained from women undergoing gamete intra-Fallopian transfer procedures who had been treated with gonadotrophin-releasing hormone analogue and gonadotrophins. Only follicles with oocytes of apparently comparable maturity were considered. Granulosa cells from large and small follicles (> or = 18 and < 15 mm diameter respectively) collected from each patient were cultured separately for up to 48 h in the presence or absence of follicle-stimulating hormone (FSH: 50 ng/ml) or insulin (at varying doses, 0.005-25 mg/ml). We found that aromatase activity was elicited by FSH plus insulin, but not by FSH alone, in granulosa cells from both large and small follicles. Progesterone production was maximal in granulosa cells from large follicles, and in these cells was insensitive to further stimuli, in contrast with those collected from small follicles. Prostaglandin oestradiol was secreted in large amounts by granulosa cells from large follicles. Cyclic adenosine monophosphate (cAMP) concentration did not differ between cells from large and small follicles. Our data demonstrate that there are significant differences in granulosa cells derived from different sized follicles with oocytes of apparently comparable maturity.