Structural analysis of oval‐cell–mediated liver regeneration in rats

We have analyzed the architectural aspects of progenitor‐cell–driven regenerative growth in rat liver by applying the 2‐acetaminofluorene/partial hepatectomy experimental model. The regeneration is initiated by the proliferation of so‐called oval cells. The oval cells at the proximal tips of the ductules have a more differentiated phenotype and higher proliferative rate. This preferential growth results in the formation of a seemingly random collection of small hepatocytes, called foci. These foci have no clonal origin, but possess a highly organized structure, which shows similarities to normal hepatic parenchyma. Therefore, they can easily remodel into the lobular structure. Eventually, the regenerated liver is constructed by enlarged hepatic lobules; no new lobules are formed during this process. The foci of the Solt‐Farber experimental hepatocarcinogenesis model have identical morphological features; accordingly, they also represent only regenerative, not neoplastic, growth. Conclusion: Progenitor‐cell–driven liver regeneration is a well‐designed, highly organized tissue reaction, and better comprehension of the architectural events may help us to recognize this process and understand its role in physiological and pathological reactions. (HEPATOLOGY 2012)

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