Histochemical demonstration of l-amino acid-tetrazolium reductase

Summary A method for the histochemical demonstration of l-amino acid-tetrazolium reductase is described. The diformazan deposition was obtained with l-leucine as substrate and no precipitate was present when l-serine and l-lisine were used. In the kidney the reaction was positive in the podocytes, the cells of proximal and distal convoluted tubules, in the ascending limbs of Henle and in the cells of the collecting tubules. In the liver the reaction was positive in the cytoplasm of the hepatocytes. The reaction pattern suggests that it is predominantly extramitochondrial. The specificity of this method is discussed.