Maintenance and Function of Corpora Lutea in Rabbits Depend on Estrogen

Abstract

Pregnant rabbits with one X-irradiated ovary which contained normal-appearing corpora lutea (CL) and interstitial tissue aborted after removal of the contralateral normal ovary containing all ovarian components. The suspicion that estrogen may be essential for CL maintenance and function was confirmed by the injection of estradiol (2-4 [mu]g/day) into rabbits with only an X-irradiated ovary containing just CL and interstitial tissue. Pregnancy was maintained in these females and both the CL and the ovarian effluent blood contained chemically measurable quantities of progesterone. Withdrawal of estrogen caused cessation of progesterone synthesis and secretion and led to abortion. At doses used, neither purified NIH-LH [hiteinizing hormone]nor crude anterior pituitary powder could, in the absence of estrogen, maintain either the morphology of corpora lutea, or the synthesis of progesterone, or pregnancy. The conclusion is reached and documented that estrogen may act directly on the CL but whether its action is only luteotrophic, or both luteotrophic and steroldogenic, remains to be determined.