Action of Estrogen on Release of Hypophyseal Luteinizing Hormone

Abstract

The pituitaries of adult 9 rats, under normal estrogen influence, stimulated moderate lu-teinization in normal and hypophysectomized recipient immature 9 rats. The pituitaries of adult [female] rats freed of estrogen stimulation through oophorectomy, invariably caused extensive luteinization of the recipient ovaries. This indicated that liberation of the hypophyseal luteinizing factor was minimal in the absence of estrogen; the factor remaining stored within the pituitary gland. Release of the luteinizing factor by estrogen was suggested also by the type of ovarian response produced by pituitaries from oophorec-tomized adult [female] rats which had been injected with estradiol benzoate daily for 30-45 days. These pituitaries produced follicular development but no corpora lutea, due to removal of the luteinizing factor by the estrogen treatment.