The exfoliating cervico-vaginal surface. II. Scanning electron microscopical studies during the estrous cycle in mice.

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.