Distribution of organelles and membranes between hepatocytes and nonhepatocytes in the rat liver parenchyma. A stereological study

Abstract

When biochemical studies on the liver are interpreted, the sinusoidal cells frequently receive little attention because, compared to hepatocytes, their contribution to subcellular fractions is assumed to be relatively insignificant. A systematic stereologic analysis of liver parenchyma was therefore performed in order to determine the distribution of organelles and membranes between hepatocytic and nonhepatocytic cells, namely endothelial, Kupffer, and fat storing cells. The livers were fixed by vascular perfusion and the data were corrected for systematic errors due to section thickness and compression. The extracellular space compartment includes the lumina of sinusoids (10.6%), the space of Disse (4.9%), and the bile canaliculi (0.4%). Hepatocytes constitute 78% of parenchymal volume; the nonhepatocytes account for 6.3% and consist of 2.8% endothelial cells, 2.1% Kupffer cells, and 1.4% fat storing cells. The nonhepatocytes contribute 55% of the volume of lipid droplets in the liver, 43% of the lysosomes, and 1.2% of the mitochondria. Although the nonhepatocytes account for only 8% of the total surface area of parenchymal membranes, they contain 26.5% of all the plasma membranes, 32.4% of the lysosomal membranes, 15.5% of the Golgi apparatus, 6.4% of the endoplasmic reticulum, and 2.4% of the mitochondrial membranes. The data demonstrate the extent to which nonhepatocytic organelles can potentially contaminate fractions used for biochemical studies. Particularly important for the interpretation of studies on lysosomes, plasma membrane, and Golgi apparatus is the finding that an appreciable part of these organelles may be derived from cell types other than hepatocytes.