ABSTRACT: A semiquantitative immunohistochemical technique for the detection of N-acetyl α-D-neuraminic acid, N-acetyl β-D-glucosamine and its β-(1 ŕ 4)-linked internal chains, α-D-glucopyranosyl and α-D-mannopyranosyl and its α-(1 ŕ 2)-linked internal chains and sterically related, nonreducing, end-chain residues of oligosaccharide chains of glycoproteins or glycolipids on the surface of membranes was developed using Con A and wheat germ lectins.
When this method was applied to the localization of carbohydrate receptors on the membrane of the normal human spermatozoa, it was found that the Con A and wheat germ lectin receptors were mainly located in the equatorial and post nuclear cap with few receptors located in the acrosome and neck. None of them were found in the intermediate segment plus tail.
Con A receptors were α-D-mannopyranosyl end-chain residues and wheat germ lectin receptors were N-acetyl β-D-glucosamine (1 ŕ 4)-linked internal chains. These groups occur together in the oligomannosidic type of N-glycosidic-linked oligosaccharide chains of glycoproteins and so the use of both lectins on desialycated membranes or on those which contain nonclustered N-acetyl neuraminic acid residues may be of help to localize this type of glycoprotein oligosaccharide chains.
Con A receptors were not removed after proteases digestion, suggesting the possibility that they are part of intrinsic spermatozoal antigens.