Morphometric Analysis of Rat Hepatocytes After Total Biliary Obstruction

Abstract

Using light and electron microscopic morphometric techniques, the effects of 48 hr of extrahepatic biliary obstruction on hepatocyte structure were examined in the rat. Liver cells near the portal area were compared to those in the centrilobular regions of the hepatic lobule. Observations on the normal animals confirm earlier evidence of quantitative differences in the surface density of organelles in hepatocytes located within different regions of the lobule. A striking difference in the quantity of the Golgi complex in the two areas of the lobule was noted for the first time, with the portal cells containing a significantly greater quantity of this organelle than centrolobular hepatocytes. After 48 hr of total obstruction, most of the previously reported qualitative changes in the canalicular and pericanalicular regions were confirmed. Morphometric analysis at the light-microscopic level showed an increase in the number of cells and a decrease in cell size in those cells near the portal area were compared to those in the centrolobular regions of the helar level demonstrated a significant decrease in both rough and smooth surfaced endoplasmic reticulum in cells of both zones, a finding in marked contrast to the hypertrophy of smooth endoplasmic reticulum suggested by other investigators on the basis of qualitative assessments. There was also a striking decrease in the amount of the Golgi complex, limited to cells in the portal regions. In addition, in all zones a decrease in the volume density of mitochondria and lysosomes was noted, whereas the volume of microbodies was increased. It is suggested that this loss in total membrane material within the cell may be secondary to the degranulation and decrease in total surface area of rough surfaced endoplasmic reticulum, an organelle thought to be responsible in part for the synthesis of new cellular membranes. These observations suggest that present concepts concerning the pathogenesis of cholestatic liver disease require reappraisal.