Histochemistry of glycoconjugates in the skin of the bovine muzzle, with special reference to glandular structures

The distribution of glycoconjugates in the muzzle of young adult Holstein cows has been studied by means of selected light-microscopic histochemical methods, including lectin histochemistry. In the skin layers, strong reactions were confined to intercellular substances in between the cells of the vital epidermis, exhibiting neutral glycoconjugates mainly with alpha-D-galactosyl and N-acetyl-D-galactosaminyl residues. In the nasolabial glands, distinctly positive staining for neutral glycoproteins with various saccharide residues (alpha-D-galactose, alpha-N-acetylgalactosamine, D-galactose-beta(1----3)D-N-acetylgalactosamine, beta-D-galactose), and for smaller amounts of acidic glycoconjugates, was found in the secretory cells and the luminal secretion. The cells of the excretory duct system showed weak to moderate reactions (alpha-D-galactose, beta-D-galactose), only the collecting ducts reacted positively for acidic glycoproteins with sialyl residues. The results obtained are discussed in view of muzzle function, with special reference to the salivary nature of the secretion of bovine nasolabial glands.