Granulosa and thecal cells from human ovarian follicles under growth: steroid formation in vitro and responsiveness to human chorionic gonadotropin.

In order to characterize the patterns of steroid production and gonadotropin responsiveness in growing human follicles, follicular thecal and granulosa cells were incubated for two hours in the presence or absence of human chorionic gonadotropin (hCG). After incubation, tissue cyclic AMP (cAMP) levels and medium content of progesterone (P), androstenedione (A) and estradiol-17 beta (E) were determined. A was the dominant steroid formed by the thecal cells, regardless if these were derived from small (diameter: 4-7.5 mm) or from large (diameter: 8-15 mm) follicles. Granulosa cells from small follicles formed minimal amounts of all steroids measured, while granulosa cells from large follicles produced considerable amounts of E in vitro. Thecal cells from both small and large follicles increased their production of cAMP in the presence of hCG. Steroid formation was significantly increased by hCG in thecal cells from large follicles only. Granulosa cells from large follicles responded to hCG in vitro with increased cAMP and steroid formation, while granulosa cells from small follicles appeared insensitive to hCG in vitro.