Glycoconjugates of the intestinal epithelium of the domestic fowl (Gallus domesticus): a lectin histochemistry study

Abstract

A lectin histochemical study was performed on formalin-fixed paraffin-embedded tissues of duodenum, jejunum, ileum, caecum and colon from six fasted and six non-fasted 8-week-old chickens (Gallus domesticus). The purpose of this study was to identify in situ the pattern of carbohydrate residues present on the luminal surface of the intestinal epithelium. Ten biotinylated lectins with different sugar specificities were used as probes, and avidin-biotin-peroxidase complex (ABC) was used as a 'visualant'. The most significant finding was the binding pattern of Lens culinaris agglutinin to various segments of the intestines. The luminal surface of the small intestinal epithelium did not stain with this lectin. In the colon the luminal surface was lightly stained, while the caecal luminal surface was intensely stained. Throughout the intestine the luminal surface stained with Canavalia ensiformis agglutinin, Ricinus communis agglutinin-I and wheatgerm agglutinin, but it did not stain with Dolichos biflorus agglutinin. These findings indicated that, throughout the intestine, the luminal surface contains glycoconjugates with either N- or O-linked glycoprotein, or both, with terminal non-reducing beta-galactosyl and sialyl residues. Furthermore, the caecal surface is rich in N-linked glycoproteins with an alpha-(1----6)-linked fucosyl residue near the glycosidic linkage. The potential significance of these observations and the role of glycoconjugates in host-parasite interaction (i.e. Eimeria sp. versus Gallus domesticus) are discussed.