Ultracytochemistry of glycosylation sites of rat colonic mucous cells with labeled lectins.

Abstract

The mucous glycoproteins of mucous cells in the lower half of the rat proximal colon were examined ultracytochemically to study the intracellular sites of glycosylation in relation to the cell differentiation and the functional polarity of the cell organellae using a combination of a hydrophilic resin embedment and a postembedding staining technique with lectin gold com plexes.In the immature mucous cells located near the branching point of the glandular crypt, the Golgi stacks and mucous granules were stained with soybean agglutinin (SBA), Ricinus communis agglutinin-I (RCA-I) and Helix pomatia agglutinin (HPA). In the mature mucous cells at the bottom of the crypt, the cis region of the Golgi stack was stained with SBA, a few intermediate saccules were stained with RCA-I, and both the cis and trans sides of the cisternae and mucous granules, but not the intermediate lamellae, were stained with HPA. After neuraminidase digestion of ultrathin sections, the RCA-I binding sites were greatly increased. Ulex europeus agglutinin-I (UEA-I) and Limax flavus agglutinin (LFA) positively stained the trans side lamellae and mucous granules of the mucous cell at the bottom of the glandular crypt.The processing of the glycosylation of the mucous glycoprotein in the lower half crypt of the rat proximal colon was partly clarified electron microscopically.