A histochemical approach to glycan diversity in the urothelium of pig urinary bladder

Intracellular glycans in the urothelium of urinary bladder of 10 adult male Landrace pigs were characterized in situ by immunohistochemical detection of Muc1 mucin by anti MUC1 from rabbit, conventional histochemical techniques (Periodic‐Acid Schiff, Alcian Blue pH 2.5, High‐Iron Diamine), and binding with 13 lectins (PNA, DBA, RCA‐I, WGA, SBA, BSI‐B4, ConA, AAA, UEA‐I, LTA, LFA, MAA‐II, SNA) combined with chemical and enzymatic pre‐treatments (β‐elimination, desulfation and neuraminidase) to gather reference data for this model animal. Muc1 mucin was detected in the secreting granules of superficial cells and the underlying layer of intermediate cells. The secreting granules in both intermediate cells and superficial cells were rich in carbohydrates, with the oligosaccharidic chains mostly O‐linked to proteins. Glycoproteins were prevailing over glycosaminoglycans (GAGs). In both superficial and intermediate cells sulfated and/or sialylated glycans were present, sulfation decreasing in the deeper layers. Lectin‐binding detected presence of terminal sialic acid linked mostly in α2,6 to GalNAc, Gal terminal or subterminal to sulfates, GalNAc, GlcNAc, and Fuc, mostly linked in α1,6, α1,3 α1,4 and α1,2 to GlcNAc or Gal, but not to lactosamine chains. Except for fucosylation, the oligosaccharidic chains in the glycoproteins of the urothelium of pig urinary bladder were similar to those linked to human MUC1, which is fundamental in cell adhesion and immunological processes in the urothelium. The co‐distribution of Muc1 and saccharidic residues suggests that many of them are linked to the glycoprotein.