STUDIES ON MICROPEROXISOMES IV. INTERRELATIONS OF MICROPEROXISOMES, ENDOPLASMIC RETICULUM AND LIPOFUSCIN GRANULES

Abstract

Previous light microscopic studies have shown that the lipofuscin granules of human hepatocytes oxidize 3,3'-diaminobenzidine (DAB). This DAB reactivity has been examined by electron microscopy. Incubation in an alkaline DAB medium demonstrates that the acid phosphatase-rich areas, containing ferritin-like grains, are DAB-positive. Close spatial relations of the lipofuscin granules with smooth endoplasmic reticulum and with microperoxisomes are demonstrated. These interrelations probably have functional significance for lipid storage in the lipofuscin granules. The relations also form the basis for speculations regarding microautophagy and the accumulation of ferritin and other cytosol constituents within the lipofuscin granules.