Liver cells. Coloured scanning electron micrograph (SEM) of liver cells (hepatocytes), several of which are undergoing undergoing cell division (cytokinesis, far left). Hepatocytes are specialised epithelial cells and make up approximately 80% of the mass of the liver. They are arranged into irregularly shaped, polygonal units known as lobules. Each lobule surrounds a central vein, which is a branch of the hepatic vein (not seen). Hepatocytes are involved with the various functions of the liver, including metabolism, detoxification of the blood and bile production. Magnification: x1800 when printed 10 centimetres wide.