6/14/2023 0 Comments Download project zone 2 for free![]() During steady-state homeostasis, zone 1 cells near the portal vein decreased in number over time, as did zone 3 cells near the central vein on the opposite end of the lobule. In contrast to the idea that all hepatocytes across the lobule contribute equally to regeneration, we identified major differences between hepatocytes from different locations. Recently, single-cell profiling has enriched our understanding of the extraordinary diversity of hepatocytes, but this “zonal” heterogeneity has not been functionally interrogated in the context of tissue homeostasis, because the critical genetic labeling tools have not been available. Although hepatocytes appear histologically homogeneous, the liver lobule is actually organized into concentric zones, or rings, in which hepatocytes express different metabolic enzymes across the portal vein–to–central vein axis through which blood flows. Multiple studies have reported that disparate cell populations in the liver serve as rare stem cells, whereas others have proposed that most hepatocytes are similar in their regenerative activity regardless of position or function. However, there has been considerable debate about the source of new liver cells that contribute to tissue growth, maintenance, and regeneration. The liver’s remarkable capacity to maintain proper tissue mass after injury has been known since ancient times.
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