LIGHT MICROSCOPIC STUDY OF THE PEROXIDATIC ACTIVITY OF CATALASE IN FORMALDEHYDE-FIXED RAT LIVER

The peroxidatic activity of rat liver catalase was demonstrated by histochemical staining with 3,3'-diaminobenzidine as hydrogen donor. The activity was so weak that its location was hard to identify in formaldehyde-fixed cells, although high catalatic activity was present, as evidenced by the production of bubbles upon the addition of hydrogen peroxide to the incubation medium. Pretreatment of fixed sections for 60 min at 37°C with formamide, urea or trypsin enhanced the peroxidatic activity significantly. The reaction granules scattered throughout the cytoplasm of the parenchymal cells probably correspond to the peroxisomes.