Hepatocyte cytodifferentiation and cell-to-cell communication

Coordination of functional diversity with compensatory adaptability requires that the cellular constituents of a tissue or an organ develop intricate communication networks. Such functional needs also dictate that stable alterations in differential gene expression, i.e., cytodifferentiation, be part of the adaptive response. The liver is a multifunctional organ involved in the central coordination of complex metabolic and homeostatic processes. The primary functions of the mammalian liver in maintenance of homeostasis with respect to such parameters as circulating levels of glucose, synthesis and secretion of plasma proteins, and provision of complex lipids are carried out by the organ’s major cell type, the parenchymal hepatocyte. Although mammalian liver is composed of about 95% parenchymal hepatocytes (80% by volume), large numbers of Kupffer cells, vascular endothelial cells, lipocytes, and bile duct epithelial cells comprise the remainder of the hepatic cell population and are increasingly recognized as essential in conditioning parenchymal cell function.