Human hepatic stimulator substance (hHSS) was extracted from the liver of 4─6 month fetus from healthy pregnant women according to the method of LaBrecque. The bioactivity of hHSS was determined by measurement of the rate of 3H-thymidine incorporation into the hepatocyte DNA after injection of hHSS into the abdominal cavity of partial hepatectomized rats. The results showed that hHSS could stimulate the synthesis of hepatocyte DNA (P<0.01).The model experimental liver injury established by hypodermic inject...