Growth of mouse vaginal epithelial cells in culture: functional integrity of the estrogen receptor system and failure of estrogen to induce proliferation.

Normal mouse vaginal epithelial cells isolated from ovariectomized ca. 40-day-old BALB/cCrg1 mice were purified by Percoll density gradient centrifugation and grown in primary culture using a collagen gel matrix and a serum-free complete medium. During the 9-day culture period, a 6-fold increase in cell number was observed. Addition of estrogen to the medium did not enhance epithelial cell proliferation. In fact, all doses of estrogen (180 fM to 18 nM) were inhibitory, resulting in only a 3- to 4-fold increase in cell number by day 9 of culture. Continuous exposure to estradiol (1.8 nM) for 9 days in the serum-free complete medium resulted in a decrease in cytosolic estrogen receptors with associated nuclear accumulation of estrogen receptors. A corresponding increase of cytosolic progestin receptors was also observed, indicating that no qualitative modification of the estrogen receptor system had occurred. Thus, despite its effectiveness in specific product synthesis (progestin receptors), estrogen does not stimulate proliferation of vaginal cells in this culture system, but rather inhibits epithelial cell proliferation.