The histochemical demonstration of sialic acid residues in pancreatic islets.

Using a modified colloidal iron reaction in connection with neuraminidase extraction test 3 different sialic acid-containing components have been demonstrated in pancreatic islets comprising golgi region and glycocalyx layer of islet cells and intrainsular capillary walls. The colloidal iron positive cationophilia increased markedly after treatment with alkali; an effect which might be due to deesterification, thus exposing additional free carbonyl groups of sialic acid residues.