The exfoliating epithelial surface of the ectocervix (pars vaginalis) and the vagina from normal mice was studied by scanning electron microscopy during the four main phases of the ovulatory cycle, and after estrogen administration. At proestrus, the epithelial surface usually presented cobblestone-like structure furnished with thin microvilli; at estrus, large, flat mosaics covered by long, convoluted microrugae; at metestrus, the presenting cellular surfaces were of intermediate size (i.e., between cobblestone and mosaics) having fragmented microrugae; and at diestrus, by mosaics or intermediate structures covered by microvilli. Estrogen administration to intact and oophorectomized animals resulted in flat mosaics and large numbers of loosely attached cells with rolled-up borders which permitted the observation of the basal surface of the cells. In those animals the apical aspect of the cells which lined the lumen showed convoluted microrugae with circular configuration, while the basal aspect of such cells had club-tipped microvilli. The findings were correlated with post-scanning histological examination in all animals.
PIP: The cyclical scanning electron microscope changes taking place both in the exocervical and in the vaginal epithelia during the 4 main phases of the estrous cycle in mice are described, and observations of the effe ct of high doses of estrogen on the epithelia are presented. The epithe lial surface usually presented cobblestonelike structures with thin microvilli at proestrus, large flat mosaics covered by long convoluted microrugae at estrus, cellular surfaces of intermediate size fragmented microrugae at metestrus and mosaics or intermediate structures covered by microvilli at diestrus. Estrogen administration resulted in flat mosaics and large numbers of loosely attached cells with rolled up borders which permitted the observation of the basal lumen revealed convoluted microrugae with circular configuration, while the basal aspect of such cells had club-tipped microvilli. The data were correlated with postscanning histological examinations.