Lectin histochemical detection of special sugars on the mucosal surfaces of the rat alimentary tract.

Surfaces of the most luminal positions of mucosae are fundamental settlement sites of indigenous bacteria throughout the rat alimentary tract. In these positions, also epithelial cell-shedding sites, the special sugar expression in the glycocalyx is very important as it provides possible ligands of bacterial lectins for attachment to epithelial cells. Therefore, the sugar expression in glycocalyx of epithelial cells was lectin-histochemically surveyed using 21 lectins throughout the rat alimentary tract. From the tongue to the nonglandular part of the stomach, α-D-Man, α-D-Glc and α-D-GalNAc were detected on the surface of the keratinized stratified squamous epithelium. In the glandular part of the stomach, α-D-Man, β-D-Gal-4GlcNAc, D-Gal, D-GalNAc, D-GlcNAc, α-L-Fuc- α-D-Gal-β(1-4)GlcNAc and bisected triantennary N-glycans were detected on the surface of gastric superficial epithelial cells. From the duodenum to the ileum, (GlcNAc)(2-4) was expressed exclusively on the epithelial cells in the apical portions of the intestinal villi. From the cecum to the rectum, α-D-Man, β-D-Gal-4GlcNAc, D-Gal, D-GalNAc, α-D-Gal(1-3)D-GalNAc, (GalNAc)(n) and NeuNAc were expressed on the intestinal superficial epithelial cells. These results suggest that special sugars are expressed on the most luminal portions of mucosae as exclusive epithelial cell-shedding sites, and that sugar expression differs among the various segments of the alimentary tract. These site differences might reflect differences in resident bacterial species in the rat alimentary tract.