Morphological changes on surfaces of vaginal epithelial cells from normal cycling (all the four phases) and estrogen primed rats (during neonatal period) at various time points were studied. Non-keratinized cells were covered with uniformly distributed short microvilli. Epithelial cells at 60 day old estrogen primed animals and from estrus rats showed characteristic microridges on their surfaces. Estrus cycle starts only after 90-100 days in normal growing rats, however, in estrogen primed rats epithelial cells of 60 day old animals showed microridges which are comparable to those of exfoliated cell surfaces. Under in vitro condition, vaginal epithelial cells grown in Ca++ and steroid free medium showed sparsely distributed short, blunt microvilli on the surface, but when the medium was supplemented with estradiol 17 beta, the cell surface showed microridges instead of microvilli. Present in vivo and in vitro studies indicated that the microridges on cell surface are the characteristic feature of the keratinized cells of vaginal epithelium.