PRINCIPLES OF TOXICOLOGY

5.1 THE PHYSIOLOGIC AND MORPHOLOGIC BASES OF LIVER INJURY 115
Figure 5.4 Liver section from mouse given an hepatotoxic dose of acetaminophen. With acetaminophen, liver
cell swelling and death characteristically occurs in regions around the central vein (Zone 3, arrow); cells near the
portal triad (Zone 1, arrow head) are spared.
There are several types of liver cells. Hepatocytes, or parenchymal cells, constitute approximately
75 percent of the total cells in the human liver. They are relatively large cells and make up the bulk of
the hepatic lobule. By virtue of their numbers and their extensive xenobiotic metabolizing activity,
these cells are the principal targets for hepatotoxic chemicals. The sinusoids are lined with endothelial
cells. These cells are small but numerous, making up most of the remaining cells in the liver. The
hepatic microvasculature also contains resident macrophages, called Kupffer cells. Although comparatively
few in number, these cells play an important role in phagocytizing microorganisms and foreign
particulates in the blood. While these cells are a part of the liver, they are also part of the immune