SENSIBILITY OF OVARY TO GONADOTROPIN

Abstract

1. In order to investigate effects of steroids on the activity of chorionic gonadotropin in rabbits, its minimum doses to induce ovulation were compared in rabbits administered estradiol benzoate, progesterone, norethisterone, testosterone propionate, progesterone with estradiol benzoate, and tosterone propionate with estradiol benzoate, and in adrenalectomized rabbits. And it was found that estrogens increased sensibility of the ovary to chorionic gonadotropin, while gestagens and androgens decreased it. The sensibility was also decreased after adrenalectomy in more than 5 days.2. For the object of investgating effects of steroids on the action of pregnant mares' serum gonadotropin (PMS), estradiol benzoate, methylestrenolone and norethisterone were administered in combination with PMS to normal immature and hypophysectomized immature rats, and their ovaries were compared both macroscopically and histologically with those of animals given PMS alone. From the results it was inferred that the inhibition of PMS action by estrogen would be effected through the hypophysis. Nearly the same was inferred concerning the action of norethisterone. Methylestrenolone, however, it was discussed, would exert direct action on the ovary as well as indirect action through the intermediation of the hypophysis. In the hypophysectomized animals, increase in medium-sized follicles without antrum and decrease in degenerative changes of ova and granulosa were observed as direct effects of estrogen on the ovary, and fibrotic changes of interstitial tissue, inhibition of corpus lnteum formation and degenerative changes of corpus luteum as those of methylestrenolone.