METABOLISM OF ANDROSTENEDIONE BY HUMAN OVARIAN TISSUES INVITRO WITH PARTICULAR REFERENCE TO REDUCTASE AND AROMATASE ACTIVITY

The ability of granulosa and theca cells of the human ovarian follicle at different stages of development, as well as stromal and luteal tissues from human ovaries to metabolize androstenedione (Δ4) to testosterone (T), dihydrotestosterone (DHT), estrone (E1) and estradiol (E2) with or without exposure to additional amounts of follicle-stimulating hormone was investigated by in vitro experiments. The results show that an the aforementioned ovarian tissues metabolized Δ4 to DHT. Indeed, with the exception of estrogen-secreting granulosa cells from large antral follicle (>10 mm diameter) and possibly also luteal tissue from mid-luteal phase ovaries, the various ovarian tissues preferentially metabolized Δ4 to DHT instead of E (E1 + E2). Although thecal tissue is a major source of Δ4 in human ovaries it is concluded that the granulosa cells do not interact with the theca for the synthesis of E as the follicle enlarges from 1 to 10 mm in diameter. Indeed, excessive thecal °4 during this growth phase probably inhibits normal follicular development. However, as the follicle enlarges beyond 10 mm in diameter, and as the granulosa cells begin to preferentially metabolize Δ4 to E, the two cell-types of the follicle may increasingly interact to enhance the follicular output of E. © 1979.