A frequent misinterpretation in current research on liver fibrosis: the vessel in the center of CCl4-induced pseudolobules is a portal vein.

Carbon tetrachloride-induced liver injury is a thoroughly studied model for regeneration and fibrosis in rodents. Nevertheless, its pattern of liver fibrosis is frequently misinterpreted as portal type. To clarify this, we show that collagen type IV+ "streets" and alpha-SMA+ cells accumulate pericentrally and extend to neighbouring central areas of the liver lobule, forming a 'pseudolobule'. Blood vessels in the center of such pseudolobules are portal veins as indicated by the presence of bile duct cells (CK19+) and the absence of pericentral hepatocytes (glutamine synthetase+). It is critical to correctly describe this pattern of fibrosis, particulary for metabolic zonation studies.