Identification of sugar residues in secretory glycoconjugates of olfactory mucosae using lectin histochemistry

Abstract

Lectin histochemistry at the light microscope level was used to determine the distribution of sugar residues in secretory cells of the olfactory mucosae of salamander, hamster, and mouse. Differences in sugar composition and distribution of glycoconjugates found in sustentacular cells and acinar cells of Bowman's glands of these three animals were characterized. Oligosaccharides in secretory products of sustentacular cells in salamander olfactory mucosa contained sialic acid, galactose (Gal), N-acetylgalactosamine (GalNAc), N-acetylglucosamine (GlcNAc), fucose, and mannose residues. Glycoconjugates of these cells lacked terminal galactosyl-beta-(1,3)N-acetylgalactose (Gal beta 1,3GalNAc) residues. The sequences Gal beta 1,3GalNAc, N-acetyllactosamine (Gal beta 1,4GlcNAc), and GalNAc were penultimate to sialic acid residues. Sustentacular cells of mouse and hamster did not appear to contain O-linked oligosaccharides but stained for mannose-containing N-linked oligosaccharides. Glycoconjugates of acinar and duct cells of Bowman's glands in the salamander, hamster, and mouse contained variable amounts of beta(1,4)GlcNAc residues, and terminal N-acetyllactosamine, Gal beta 1,3GalNAc, and GalNAc residues. In the salamander, glycoconjugates of acinar cells possessed terminal GlcNAc residues but were not sialylated, while those of hamster and mouse generally stained for sialic acid but did not possess terminal GlcNAc residues. Secretory products of a subpopulation of rodent acinar cells also contained penultimate Gal beta 1,3GalNAc residues. Staining for sialic acid, Gal, GalNAc, and GlcNAc in glycoconjugates of rodents was often limited to a sub-population of Bowman's glands. This was especially noticeable in the mouse.