Immunohistological localization of alpha 1-fetoprotein in normal and diseased liver.

Cellular alpha 1-fetoprotein (AFP) is localized by light and electron microscopic immunoperoxidase methods. For light microscopic studies we employed ethanol-acetic acid fixed and paraffin embedded liver blocks. For the ultrastructural localization of AFP, formaldehyde-glutaraldehyde fixed tissues were used in preembedding phase. The occurrence of AFP was studied in normal and diseased livers of mice and rats: (a) fetal and neonatal livers; (b) liver regeneration after CCl4 intoxication; (c) chemical hepatocarcinogenesis. During ontogenesis, AFP is detected in perinuclear spaces, in lamellae of the RER and in the Golgi apparatus of fetal and postnatal hepatocytes. After CCl4 intoxication of low and high AFP producing mouse strains, cellular AFP is found in hepatocytes of portal, periportal and intermediate zones. Hepatocytes in front of the necroses usually contain the strongest reactions. In early stage of hepatocarcinogenesis, AFP is localized in proliferating oval-shaped cells when injured livers regenerate. At the stage of malignant conversion, distinct AFP staining and non-AFP staining hepatocellular carcinomas occur.