Hormonal modification of epithelial differentiation and expression of cell surface heparan sulfate proteoglycan in the mouse vaginal epithelium. An immunohistochemical and electron microscopic study.

Immunohistochemical staining of a cell surface antigen was evaluated in the adult mouse vaginal epithelium at different stages of the estrous cycle and in response to exogenous sex hormones and endocrine ablation. The antigen is recognized by a monoclonal antibody directed against the core protein of a heparan sulfate-rich proteoglycan from mouse mammary epithelial cells. Vaginal epithelium at estrus showed the most intense staining; cells of the basal and intermediate layers stained, but the more superficial parakeratotic, cornified, and sloughing layers did not. At metestrus and diestrus, immunostaining was limited to basal cells and some deeper intermediate cells. The staining was absent from the more superficial layers which were invaded by leukocytes. At late diestrus and proestrus, staining was primarily in the intermediate cells; staining was absent from parakeratotic and basal cell layers. There was no staining of submucosal cells throughout the estrous cycle. In ovariectomized mice, staining of the epithelium was reduced in intensity. Diethylstilbestrol treatment of ovariectomized mice increased the intensity and extent of epithelial staining and produced a state comparable to that seen at estrous. Administration of a combination of progesterone and estradiol to ovariectomized mice elicited vaginal stratification and mucification, a state comparable to that observed in diestrus in which basal and intermediate layers stained while the apical mucified cells did not. In animals expressing natural or diethylstilbestrol-induced estrus, electron microscopic immunoperoxidase staining revealed the presence of the antigen on the surface of cell processes in the intercellular spaces between vaginal epithelial cells. Cuprolinic blue staining for glycosaminoglycan using the critical electrolyte concentration method demonstrated filamentous structures on the epithelial surface in the same location to that of the antigen. The stained filaments were reduced by treatment with heparitinase, but not with chondroitinase ABC or heparin, suggesting that they contained heparan sulfate glycosaminoglycan. These data suggest that as vaginal epithelial differentiation fluctuates during the estrous cycle in response to changing levels of estrogens and progesterone, expression of a cell surface heparan sulfate proteoglycan undergoes dramatic changes spatially and quantitatively.