Glycoconjugate histochemistry of bovine Brunner glands

The principal aims of this study have been to elucidate the nature of glycoconjugates produced by the two distinct parts of bovine Brunner glands, peripheral and central areas of lobules, and to investigate the presence of sialyl acid residues. Bovine duodenal tissues, embedded in paraffin wax, were investigated by means of both conventional histochemical methods (PAS, AB, HID) and biotinylated lectins (Con A, DBA, SBA, GS-I-B4, PNA, sWGA, GS-II, UEA-I, LPA, LFA). Conventional histochemical methods allowed us to accurately define two different areas: a central and a peripheral area. The central area, composed of secretory tubular tracts and the excretory duct, contained neutral glycoconjugates. The peripheral area was formed by both terminal alveolar and tubular secretory tracts and contained both neutral and acidic glycoconjugates, the latter partly carboxylated and partly sulfated. Lectin histochemistry confirmed differences highlighted by conventional histochemical methods and allowed us to characterise glycoprotein profiles of the preterminal and terminal tracts. The preterminal tracts and the excretory duct contained glycoconjugates with terminal D-Gal ]3(1-3)GalNAc, a-D-Gal, a/[3-D-GalNAc, a/[3-D-GlcNAc, and internal [3(1-4) D-GlcNAc and a-Man residues. The terminal tracts were characterised by terminal a-L fucose, [3-D-GalNac, a/[3D-GlcNAc, a-D-Gal, a-D-GalNAc, and sialic acid residues. Internal [3(1-4) D-GlcNAc and a-Man residues were also identified. Finally, secretion of bovine Brunner glands is characterised by both O-linked and N-linked glycoproteins: cells located in the preterminal tracts and in the excretory duct produce mainly O-linked glycoproteins while cells located in the terminal tracts produce N-linked glycoproteins.