ARGENTAFFIN AND SCHIFF REACTIONS AFTER PERIODIC ACID OXIDATION AND ALDEHYDE BLOCKING REACTIONS

Abstract

Among periodic acid Schiff pos. tissue elements there are some which become strongly argentaffin after periodic acid oxidation and are not so without it. Others are almost equally argentaffin with or without periodic acid oxidation. Still others are not argentaffin without the oxidation and are not made so by periodic acid treatment. Other argentaffin tissue elements are found which do not yield a Schiff reaction with or without periodic acid oxidation and whose reaction to Ag is uninfluenced by that oxidant. Some periodic acid Schiff neg. tissue elements occur whose natural argentaffin reaction is destroyed by interposed periodic acid oxidation. Carbonyl blocking reagents, such as cyanide, phenylhydrazine and aniline chloride, prevent the pos. Schiff reaction when interposed after periodic acid oxidation, but do not prevent Ag reduction. Methylation with hot acidulated methanol prevents pos. Schiff reactions. Methylation with hot acidulated methanol renders certain normally oxyphil tissue components intensely argentaffin. Treatment for 24 hrs. with distilled water at 60[degree]C reverses the Schiff reaction of most periodic acid engendered aldehydes. Distilled water at 60[degree]C renders non-argentaffin a number of natively argentaffin substances and reverses the argentaffin reaction created by periodic acid oxidation. The argentaffin reaction appears to be a definitely unspecific reaction for various reducing substances, and its occurrence does not by itself denote the presence of aldehyde groupings.