Image of normal human iiver parenchymal cells, where peroxisomes are stained brown with DAB by their catalase activity at pH 10.5. No counterstain was used. Prefixation was carried out in buffered formal-calcium and cryostat section of 4 µm were taken. The large brown structures in capillaries are erythrocytes that react with DAB by the peroxidatic activity of hemoglobin.