Fig. 2.

Organization of the liver lobule and acinus. Based on the local blood composition, the acinus is roughly divided into three zones, 1 periportal, 2 transitional and 3 perivenous. The periportal zone is close to the portal triad vasculature and supplied by highly oxygenated blood (O₂ partial pressure 60–70 mmHg). The perivenous zone is proximal to the central vein and receives poorly oxygenated blood (O₂ partial pressure 25–35 mmHg). If no specific zonal mechanisms are active (such as pericentral metabolic activation of many hepatotoxic compounds, because many CYP enzymes are preferentially expressed in the center of the liver lobules), toxicity becomes visible at first in the periportal region, as this is the first zone to filter blood (Allen and Bhatia 2003). Adapted from Bacon et al. (2006)