The Increased Basophilia of Tissue Proteins After Oxidation with Periodic Acid

Oxidation by periodic acid (a 1% aqueous solution for 1 hour at 37°C.) greatly enhances the basophilic staining normally present in the keratinized portions of epidermis and hair. It also induces strong basophilia in purified fibrin and in the cytoplasm of smooth and striated muscle fibers, endothelium and the cells of the pancreatic islets and acini Proof is offered that this observed basophilia differs from that of either acid mucopolysaccharides or nucleoproteins. The conclusion is reached that, besides revealing polysaccharides occurring in tissue sections, periodic acid also brings about the formation of strongly acid, basophilic groups. These acid groups have not been identified, but since they may be formed most readily in regions of high sulfur content, it is suggested that sulfide and sulfhydryl groups may be oxidized to the corresponding sulfonic acids which could account for the observed characteristics of the basophilic substances.