Steroidogenesis in vitro by human ovarian follicles during the process of atresia.

Slices of each of the six antral follicles at different stages of atresia isolated from ovaries of six patients with or without pretreatment with HCG before laparotomy, were incubated with [1-14C] acetate. Incorporation into progestins, androgens and oestrogens was assessed by the reverse dilution technique with recrystallization to constant specific activity. The greatest incorporation into androstenedione without any incorporation into progesterone was commonly observed throughout the morphologically defined three stages of atresia. In the first stage atretic follicles, characterized by coexistence of normally developed thecal cells with degenerating granulosa cells, a minute incorporation into oestradiol was identified. In the second state atretic follicles, showing hyperplasia and hypertrophy of thecal cells without granulosa cells, an increased incorporation into androgens was shown. Treatment with HCG induced similar but much pronounced changes in function and morphology. In the third stage atretic follicles, with subsiding thecal cells, a diminished incorporation into androstenedione was observed with 17-hydroxyprogesterone being the only other steroid formed in this stage. The observed qualitative and quantitative changes of steroidogenesis in vitro may be functional reflections of structural changes during the atretic process.