Immunohistochemistry of hepatic IGF-I in calf, pig, and rat

The liver appears to be the major site of synthesis of somatomedin C or insulin-like growth factor I (IGF-I), yet, the intrahepatic histological localization of this polypeptide is not well known. For this reason we investigated immunohistochemically the liver of calves, pigs, and rats, fixed by perfusion or immersion with Karnovsky solution. In all three animal species the layer of hepatocytes bordering the liver capsule was labeled by anti-IGF-I. In the pig and rats all perivenous hepatocytes were intensively labeled whereas in calves only the periportal hepatocytes contained immunoreactive IGF-I. While preabsorption of the anti-IGF-I antiserum with the antigen abolished the immunoreaction, preabsorption with insulin or IGF-II did not. No labeling occurred when immersion-fixed liver tissue was used.