Light- and electron-microscopic autoradiographic analysis of proliferating cells during the early stages of chemical hepatocarcinogenesis in the rat induced by feeding N-2-fluorenylacetamide in a choline-deficient diet.

Proliferating cells that appear after feeding the hepatocarcinogen N-2-fluorenylacetamide in a choline-deficient diet were identified by autoradiographic electron and light microscopy. Labeled cells are first seen as nondescript periductular cells 1 day after feeding carcinogen. Proliferation of duct lining cells begins at 2-3 days. For the next three weeks there is proliferation and extension of a mixture of nondescript cells and cells with a duct like appearance from the portal zone into the adjacent liver. By 3-4 weeks the entire liver lobule contains this new cell population. At 3 weeks more differentiated duct like structures are seen at the edge of the advancing new cell population. Newly appearing duct like cells differ from normal duct cells in that they contain AFP and albumin. It is concluded that the new cell population may arise from duct cells or periportal "stem" cells, or both.