Estrogen Responsiveness and the Estrogen Receptor during Development of the Murine Female Reproductive Tract

The developing uterus, vagina, and cervix of mice whose age ranged from 16 days of gestation to 90 days postnatal were examined for nuclear estrogen receptors (ERs) by autoradiographic and whole cell uptake techniques. ERs were present within mesenchymal cells of these organs throughout the entire period of development and maturation. By contrast, nuclear ER first became detectable by autoradiography in the epithelium of vagina and uterus at 5 and 6 days postnatal, respectively.
As a result of administration of the synthetic estrogen, diethylstilbestrol (DES), consecutively from 16 to 18 days of gestation, uterine and vaginal epithelial cell height was increased and epithelial secretory activity was elevated during the first 48 hr of postnatal life. Also, a single does of DES administered on the 2nd day after birth stimulated epithelial proliferation in the uterus as determined by ³H-thymidine incorporation. These typical estrogenic effects occurred in the absence of nuclear ER within the epithelium. Prenatal DES treatment accelerated the onset of ER activity within the epithelium by 2 to 3 days relative to controls. The possibility that certain effects of estrogen on epithelial differentiation may be mediated indirectly via ER positive mesenchymal cells is discussed.