Characterization of glycoconjugates in an embryonic human epithelial line and changes consequent to adaptation to a hyperosmotic medium

Cell surface and cytoplasmic glycoconjugates were characterized in embryonic human explant cells (a transformed heteroploid line) cultured in iso-osmotic medium (0.137 m NaCl) and in hyperosmotic medium (0.274 m NaCl) for 10 days in order to study the changes induced in these compounds by hyperosmoticity. Cytochemical and ultracytochemical staining selective for glycoconjugates was carried out. The following results were obtained: (1) glycoproteins, glycosaminoglycans and glycolipids are present on the cell surface and in the cytoplasm of the explant cells; (2) lectin histochemistry combined with glycosidase digestion demonstrated the presence of the disaccharides fucose-N-acetylglucosamine and sialic acid-β-galactose as terminal sequences; (3) histophotometric evaluation of lectin labelling showed a noticeable decrease in histochemical reactivity of adapted cells; (4) plasma membrane cell coat decreased in adapted cells, which was emphasized by ultracytochemical reactions and a rearrangement of glycolipids in the cytoplasm. © 1989 Chapman and Hall Ltd