Effects of Estrogen on Mitosis in Individual Cell Types of the Immature Rat Uterus1

Abstract

This study was initiated to determine the time course of estrogen action in individual uterine cell types of the immature rat uterus. Animals were treated with a single injection of estradiol-17β for various times and colchicine was administered 4 h prior to sacrifice. In the luminal epithelium, a peak of arrested mitoses was observed 24 h after hormone administration and represented ∿12% of the cell population. In contrast both the stroma and myometrium displayed a peak of arrested mitoses 36–48 h after hormone administration and the maximum value represented ∿1% of the total cell populations. These results indicate that the patterns of estrogen-induced cell division are quantitatively and qualitatively distinct in the different cell types of the immature rat uterus.