We investigated the hepatocellular peroxisomes in 27 patients with steatosis of the liver by means of catalase cytochemistry, light and electron microscopic study, and morphometry. Seven normal human livers were used as controls. In our patients, fatty liver was mainly associated with alcohol abuse or obesity. Indications for a slight decrease in catalase activity and for a proliferation were found by visual evaluation of the peroxisomes. Morphometric analysis showed a significant decrease in mean peroxisomal diameter (to 87%) and a simultaneous significant elevation in numerical density of the peroxisomes (to 188%); this resulted in a normal volume density and a significant increase (to 133%) in surface density. However, individual differences were found. No differences in peroxisomal characteristics were found between fatty livers of different causes. A significant inverse linear correlation between mean peroxisomal diameter and numerical density was found in patients with fatty livers. Because a similar correlation was also found when control data were added to the fatty liver data, we hypothesize that the peroxisomal compartment in human fatty livers is adapted in such a way to permit the same metabolic efficiency as in control livers. (HEPA-TOLOGY 1995;22:744-752.)
Peroxisomes are subcellular organelles characterized by a single tripartite membrane and a homogeneous matrix; they are often partly surrounded by cisternae of the endoplasmic reticulum. In normal human liver, peroxisomes lack matrical inclusions.' Peroxisomes contain several hydrogen peroxide-producing oxidases and hydrogen peroxide-scavenging enzymes (e.g., catalase). These and other peroxisomal enzymes intervene in several metabolic pathways such as the beta-oxidation of distinct sets of fatty acids, prostaglandins, and xenobiotic side chains, and the synthesis of bile acids, cholesterol, dolichol, and plasmalogens.2 The From the Menselijke Anatomie and Embryologie, Vrije Universiteit Brus-