Inhibition of estrogen synthesis does not inhibit luteinizing hormone-induced ovulation

In isolated, perfused rat ovaries, the addition of luteinizing hormone (LH) to the perfusion medium consistently induced follicular ruptures. These ruptures were preceded by a marked increase in the levels of estradiol in the perfusion medium. The addition of 4-hydroxyandrostene-3,17-dione (4-OH-A) to the perfusion medium blocked this increase in estradiol, but did not prevent ovulation. Levels of estradiol in follicular fluid were also reduced during perfusion with LH plus 4-OH-A, in comparison to LH alone. The conclusion drawn was that the marked rise in the production of estrogen by preovulatory follicles of the perfused rat ovary, induced by an ovulatory dose of LH, is not required for ovulation to occur.