Cell adhesion molecules in liver function and pattern formation.

In epithelia, adhesive interactions participate in specific histogenetic events and also instate a morphological polarization that is linked to the vectorial functioning of the epithelium. Cell polarity is a recurring event in differentiation, first observed in the preimplantation embryo and then during organogenesis, whereas in oncogenesis a breakdown of polarity may occur. We review here recent work on adhesive interactions in the liver parenchyma. We focus on the effect of cell-biomatrix interactions on hepatocyte function and polarization, on the integration of adhesive cell-cell and cell-matrix interactions, and on the correlation between structural differentiation and adhesion during hepatic development, regeneration, and oncogenesis. Although highlighting morphological differences between the liver and other epithelia, we stress that adhesion-mediated effects such as substratum regulation of differentiation, feedback control of matrix synthesis, and integration of intercellular and cell-matrix interactions, shown to transpire in the liver, most probably occur in other parenchymal tissues too.