Compartmental ovarian steroidogenesis in polycystic ovary syndrome.

Compartmental ovarian steroidogenesis in vitro was investigated in polycystic ovary syndrome. Basal estrogen secretion by granulosa cells ranged from 60 to 284 pg/micrograms cell protein for 24 hours and progesterone secretion from 24 to 1646 pg/micrograms cell protein for 24 hours. In three of four specimens, the addition of either 10(-5)M testosterone or androstenedione significantly increased estrogen production, demonstrating the presence of aromatase activity. Treatment with human follicle-stimulating hormone (100 ng/mL) or human chorionic gonadotropin (100 ng/mL) significantly increased the progesterone production in three of four specimens. The thecal compartment of every patient secreted significantly more testosterone and androstenedione than the capsule and stroma and more estrogen in tissue from two of the four women. The androgen/estrogen ratio was significantly greater for the theca (16.9) than the capsule (1.1) or stroma (1.7). These data demonstrate that in polycystic ovary syndrome a portion of the follicles possess the qualitative characteristics of developing follicles, granulosa cell aromatase activity and gonadotropin responsiveness, and that the theca is likely the principal site of ovarian androgen synthesis. These findings suggest that the small follicles characteristic of polycystic ovary syndrome consist of a mixed population of developing and atretic follicles and that the peripheral androgen excess is attributable to the large mass of the thecal compartment from both follicle populations.