Expression of the carbohydrate antigen CD15 in rat uterine epithelial cells during the early stages of pregnancy.

The presence and distribution of the carbohydrate antigen CD15 in rat uterine epithelial cells was determined using immunohistochemical localisation at both light and electron microscopical levels. Rat uterine tissue was examined on days 1, 3 and 6 of pregnancy and it was found that expression of CD15 was highly stage specific with negligible detection on days 1 or 3 of pregnancy but very strong expression at both light and electron microscopic levels on day 6. Electron microscopy using ferritin as marker revealed expression in the glycocalyx of the plasma membrane of uterine epithelial cells. This strongly stage-specific expression of CD15 and the extracellular surface localisation suggests an important role for this antigen during the early stages of pregnancy in the rat and implicates the molecule in attachment to the uterine epithelium.