Glycoconjugates in the Secretory Epithelium of the Mandibular Salivary Gland of Malayan Pangolin (Manis javanica)

Objective __ To reveal the distribution of glycoconjugates in the mandibular salivary gland of the Malayan pangolin (Manis javanica). Materials and Methods __ The histology and glycoconjugates histochemistry of the mandibular salivary gland in Malayan pangolin (Manis javanica) were examined by conventional histology and lectin histochemistry in combination with enzymatic (neuraminidase) digestion. Staining for conventional histology included hematoxylin and eosin (H&E), alcian blue (AB), and periodic acid Schiff (PAS). For lectin histochemistry, we used 7 lectins including Glycine max (SBA), Wheat germ agglutinin (WGA), Dolichos biflorus agglutinin (DBA), Concanavalin A (Con A), Ulex europaeus agglutinin-I (UEA-I), Ricinus communis agglutinin-I (RCA-I) and Peanut agglutinin (PNA). Intensities of staining were evaluated. Results __ Morphology of the mandibular salivary gland appears as a tubuloacinar gland with its secretory endpieces contained exclusively mucous acinar cells. A large number of acidic and neutral glycoconjugates were observed in the sections stained with AB and PAS. In the sections stained with lectins, glycoconjugates with N-acetylgalactosamine, N-acetylglucosamine, Galactosyl (β1→4) N-acetylglucosamine and mannose were present; conversely, fucose residues were not found in mucous cells of the gland. Neuraminidase digestion revealed the presence of sialic acid residues linked to Galactosyl (β1→3) N-acetylgalactosamine (PNA staining). In intercalated duct of the gland, the apical surface bordering the lumen was heavily to moderately stained with lectin SBA, WGA, DBA, UEA-I and Con A and weakly to negatively stained with AB pH 2.5, PAS, AB pH 2.5 PAS and RCA I. Conclusion __ This study demonstrated a remarkable variety of glycoconjugates in the mandibular salivary gland of Malayan pangolin. The variety may reflect different functions. KKU Vet J. 2009;19(2):162-170 http://vet.kku.ac.th/journal/