Observations on the fine structure of long-survived isolated hepatocytes inoculated into rat spleen.

Hepatic parenchymal cells which were isolated from rats and transplanted into the spleens of syngeneic rats were evaluated by electron microscopy. Fine structure of the isolated hepatocytes demonstrated that, except for a decrease in glycogen particles and focal proliferation of smooth endoplasmic reticulum, the organelles were morphologically indistinguishable from normal cells. The most striking finding was that the cytoplasmic membranes of the inoculated hepatocytes morphologically and functionally differentiated during proliferation exhibiting biliary surfaces, perisinusoidal surfaces, and other surfaces. These proliferated hepatocytes reconfigured the space of Disse and the sinusoidal structure within the splenic parenchyma. Endothelial cells with several fenestrations and fat-storing cells containing lipid droplets were also found but Kupffer cells were not detected. Electron microscopy demonstrated that adult isolated hepatocytes survived and proliferated in the rat spleen for more than 16 mo, retaining the structural elements of hepatic cytoplasm while reconfiguring a hepatic sinusoidal architecture.