Endocrine role of follicles in the regulation of corpus luteum function in the rabbit.

Abstract

In order to study the luteotrophic action of estrogen in rabbits, X-irradiation was used to destroy follicles which are the presumed sources of this hormone. Rabbits with an X-irradiated ovary containing only corpora lutea and interstitial tissue aborted following the removal of a contralateral ovary which contained all normal ovarian components except corpora lutea. In sham-operated animals, pregnancies were maintained to term, demonstrating that X-irradiation or surgical trauma did not interfere with normal corpus luteum function. It was shown experimentally that: 1) Maintenance of pregnancy by exogenous progestin following hemicastration failed to prevent regression ofcorpora lutea in the X-irradiated ovary and cessation of progesterone secretion; 2) hemicastration of pseudopregnant rabbits caused regression of corpora lutea in the X-irradiated ovary and terminated the secretion of progesterone; 3) luteinizing hormone (225 μg/day) alone and in combination with prolactin (1.5 mg/day) failed to prevent abortions and regression of corpora lutea. These observations lead to the conclusion that corpora lutea in the rabbit are directly maintained by a hormone (probably estrogen) from follicles; in the absence of follicles, hormones of pituitary or placental origins have no significant luteotrophic effects. (Endocrinology83: 509, 1968)