Light microscopical detection of H2O2-generating oxidases using cerium ions and aqueous incubation media.

Light microscopical procedures were optimized and tested for specificity for the histochemical demonstration of D-amino acid oxidase, alpha-hydroxy acid oxidase, monoamine oxidase, and xanthine oxidase using cerium ions and a visualization step originally described by Angermüller and Fahimi (1988a, b), and modified for D-amino acid oxidase by Gossrau et al. (1989). The visualization medium contained diaminobenzidine, cobalt ions, and small amounts of hydrogen peroxide. Procedures of pretreatment of cryostat sections, types of substrate, concentrations of substrates, and cerium ions were varied. Optimum procedures are reported for the detection of these oxidases in different rat tissues. The results are compared with those obtained with other methods described for the demonstration of hydrogen peroxide-generating oxidases such as the tetrazolium, Hatchett Brown, and coupled peroxidatic methods.