Preservation of cellular polarity in isolated hepatocytes. Visualization of cytoskeletal structures by indirect immunofluorescence and fluorescent staining with tetramethylrhodaminyl-phalloidin.

The distribution of actin, myosin and tropomyosin in freshly isolated and short-term cultured rat hepatocytes was investigated by use of both rhodaminyl-phalloidin staining and immunofluorescence techniques. The cytoskeletal proteins were mainly located in distinct areas of the hepatocyte membrane, corresponding to their accumulation in the bile-canalicular region of liver tissue. In freshly prepared cells, these sections resembled sharp, angled or branched bands, similar to the pattern of hemicanaliculi. During incubation in a monolayer culture, these bands were transformed to circular formations. Simultaneously, enclosed bile-canalicular spaces between undissociated hepatocytes were visualized by staining of actin, myosin, and tropomyosin. The preservation of canalicular cytoskeletal structures in isolated hepatocytes is an indication of cellular polarity. Our findings suggest a uniform association of membrane-bound F-actin with myosin and tropomyosin.