Mosaic characteristics of human endometrial epithelium in vitro: analysis of secretory markers and cell surface ultrastructure

Specific terminal carbohydrate structures and mucin-associated glycans incr ease in expression within the human endometrial epithelium during the secre tory phase of the menstrual cycle but exhibit wide intercellular variation. We postulated that variation in glycosylation between cells would produce differences in the glycocalyx and result in complex mixtures of cells beari ng different combinations of glycans. MUC-1 mucin, keratan sulphate and fuc osylated lactosaminoglycans were examined in epithelial gland fragment cult ures with antibodies (HMFG1, 5D4) and a lectin (Dolichos biflorus agglutini n). The glycocalyx was examined by transmission and high resolution scannin g electron microscopy. The data were related to patterns of expression seen in vivo. The MUC-1 mucin was expressed relatively uniformly in culture, bu t heterogeneity was evident in mucin sialylation within the epithelial cell population, Double labelling of gland explant cultures for combinations of fucosylated lactosaminoglycans, keratan sulphate and MUC-1 demonstrated ce lls expressing all combinations of these markers. Ultrastructural examinati on confirmed remarkable intercellular variation in the glycocalyx. Though t he human endometrial epithelium is relatively morphologically homogeneous, these observations reveal complex variations of cell surface glycosylation between neighbouring cells and suggest that secretory function might vary i n a similar fashion.