Aldehyde Reactions in Tissues in Relation to the Feulgen Technic

The nature of the Schiff-positive radical responsible for the Feulgen reaction was studied by several standard tests for aldehyde. Oxidative, amine, alkali, and catalytic reactions for aldehydes were used. An aldehyde reaction, similar histologically to the Feulgen, could not be produced by the oxidative and amine technics. However, by means of alkali and catalytic methods, it was possible to block the Feulgen-positive tissue radicals ordinarily released by acid hydrolysis. A second hydrolysis of the tissues (after the blocking reactions) restored most of their original Feulgen-positive characteristics.