Transitional Changes in the Surface Epithelium of the Cycling Mouse Vagina, Cervix and Uterus: Scanning Electron Microscopic Studies

During the estrous cycle, the mouse reproductive tract undergoes a number of specific morphological changes. The alterations which occur in the luminal surface of the vagina, cervix and uterus were studied by scanning electron microscopy (SEM). The stage of estrus was identified by vaginal observation, cytology and histology. The lumen of the reproductive tract was observed with the SEM at low powers of magnification as well as at the subcellular level. Surface epithelial alterations associated with mucification and keratinization of vaginal epithelium were identified by SEM; changes in the squamocolumnar junction were studied as were the cyclic variations in the mouse endometrium.This study was done to characterize the morphological appearance of the normal female mouse reproductive tract and thereby establish a normal baseline for the evaluation of samples from subsequent studies of corresponding pathologic tissue. A comparison of the similarity of the epithelial characteristics observed in normal cervix and vagina at diestrus to those in cells described by other investigators in reportedly dysplastic tissue demonstrates the need for this type of systematic approach in SEM studies.