Differential Effects of Estradiol-17β and Progesterone on the Proliferation of Glandular and Luminal Cells of Rabbit Uterine Epithelium

Abstract

A technique was developed to determine in vitro the effects of ovarian hormones administered to rabbits on the proliferation of endometrial epithelium. Using this technique, we observed that estradiol-17β stimulates the proliferation of endometrial glandular cells in intact or ovariectomized rabbits. Progesterone also induced an increase in the proliferation of both luminal and glandular epithelium of intact rabbits. Foci of cells with nuclei labeled with [³H]-Tdr suggesting active hyperplasia were observed in the luminal uterine epithelium of progesterone-treated rabbits, which seems to be related to the formation of glands characteristic of arborized endometrium. Since the ovarian hormones appear to be affecting the luminal and glandular cell populations in different ways, the fact that simultaneous administration of both of them produced a mutual antagonistic effect suggests the existence of complex regulatory mechanisms for the hormonal modulation of proliferation and differentiation in uterine epithelium.