The Histochemical Demonstration of Cytochrome Oxidase With a New Reagent for the Nadi Reaction

By synthesizing an analogue of N,N-dimethyl-p-phenylene diamine, a new reagent for the Nadi reaction was found which provided a useful histochemical method for either cytochrome oxidase (G-Nadi) or peroxidase (M-Nadi). The new agent is 4-amino-1-N,N-dimethylnaphthylamine and yields with α-naphthol, an indonaphthol purple pigment which is more stable and more satisfactorily distributed in tissue than the indophenol blue of the Nadi reaction. Thin sections may be used, some permanence of color is obtained and the granules are fine and anatomically distributed. The localization of cytochrome oxidase activity in heart, stomach, spleen, and cerebellum of the rat is described.