Development and maintenance of bile canaliculi in vitro and in vivo

The apical surfaces of hepatocytes are specialized to form the boundaries of the bile canaliculi. The canaliculi function to secrete and concentrate components of the bile and to transport the bile out of the interior of the hepatic parenchymal tissue to the epithelium-lined bile ducts. Failure of the canaliculi to form and function properly can lead to biliary stasis or release of bile components into the bloodstream, both potentially life-threatening situations. Experimental analysis of canaliculus development and function has been undertaken in a number of experimental systems, ranging in complexity from intact animals to isolated hepatocyte cell cultures. These approaches each have inherent advantages and disadvantages for studying the various aspects of canaliculus development and function. This article summarizes what is known about how the functional components of the canaliculus develop and the directions that current experimental approaches are leading in analyzing this process. Studies of model epithelial systems have begun to define how interactions between components of the cytoskeleton and plasma membrane regulate the structure of polarized plasma membranes. These results are also discussed in terms of the bile canaliculus.