FIGURE 2.

Technological advances in the study of liver zonation. Over the past century, technological advances have driven discoveries related to hepatocyte organization and function. Early observations describing structural heterogeneity were confined to microscopy techniques (Noël, 1923; Kater, 1933; Shank et al., 1959). The development of hepatocyte separation approaches (1950–1980), including perfusion techniques, fluorescent activated cell sorting (FACS), and immunohistochemistry allowed biochemical classification of hepatocyte activities (Baron et al., 1981; Gumucio et al., 1981; Lindros and Penttilä, 1985). Deep insight into the differential gene expression patterns in the hepatic lobule was accomplished in 2017, where single cell RNA sequencing revealed that fifty percent of liver genes are non-uniformly distributed (Halpern et al., 2017). The first three-dimensional (3D) multiphoton microscopy of the human liver lobule reveled disrupted bile canalicular network in nonalcoholic fatty liver disease patients in 2019 (Segovia-Miranda et al., 2019). Recently (2021), changes in gene expression patterns across the lobule were examined in different times of the day revealing yet another layer of complexity in the regulation of compartmentalization (Droin et al., 2021). Advances in mouse genetics and light microscopy now allow the use of Intravital microscopy for examination of the hepatic lobule in real time. Depicted is a projection of 3D volume of the murine lobule acquired with intravital confocal microscopy (PP, periportal; PC, pericentral; bile canaliculi in green, sinusoids in red).