Figure 1. Plasticity of the adult liver .

A simplified scheme of a liver lobule composed of a biliary duct and surrounding hepatocytes is shown. Epithelial ductal cells (also named cholangiocytes) constitute the bile ducts that collect the bile secreted by hepatocytes. A facultative quiescent stem/progenitor population in the ductal compartment (depicted in green) has been suggested by several reports. Axin2‐positive and Sox9‐positive hepatocytes have been recently described as drivers of liver homeostasis and potential facultative stem/progenitor populations. Different mechanisms involving mature cells and stem/progenitor cells have been reported during tissue regeneration. Mature hepatocytes might de‐differentiate into proliferating ductal‐like stem/progenitor cells (in red) that, in turn, expand and differentiate. Alternatively, they might re‐enter the cell cycle, re‐acquiring proliferative potential and restoring the damaged parenchyma. Regarding stem/progenitor cell response, two main mechanisms have been reported: (i) the ductal compartment can activate bipotential stem/progenitor cells (in red), which rapidly expand and differentiate into hepatocyte and ductal cells; (ii) Sox9‐positive hybrid hepatocytes can undergo extensive proliferation and generate mature hepatocytes.