Ultracytochemistry of glycoconjugates in rat Brunner's gland with labeled lectins.

Mucous glycoproteins of rat Brunner's gland were examined ultracytochemically to elucidate the intracellular localization and sites of glycosylation in relation to the functional polarity of the cell organellae using a combination of hydrophilic resin embedment and postembedding staining with labeled lectins. A few cis cisternae were stained with HPA (Helix pomatia agglutinin, specific for terminal alpha-N-acetylgalactosamine) and DBA (Dolichos biflorus aggulutinin, specific for terminal alpha-N-acetylgalactosamine). Trans cisternae as well as cisternae following secretory granules were stained with HPA and RCA-I (Recinus communis agglutinin I, specific for terminal beta-galactose). UEA-I (Ulex europaeus agglutinin I, specific for terminal alpha-L-fucose) seemed to bind to transmost cisternae rather than trans cisternae. HPA bound to the whole cisternae, but to the cis or trans cisternae depending on a cell type. Apical mucous granules were stained with UEA-I, RCA-I, and HPA, but not with DBA. DGA seemed to be a good marker of the cis side of the Golgi apparatus and cell membrane. The glycosylation of mucous glycoprotein in rat Brunner's gland was partly clarified electron microscopically.