[Evolution of hyperplastic foci in the rat liver induced by diethylnitrosamine]

The immunohistochemical localization of ligandin (L), A-protein (A) and alpha-fetoprotein (AFP) was studied in the liver of rats treated intraperitoneally with diethylnitrosamine (DENA). In early foci of altered cells there was a consecutive change in the content of antigens. The uniform content of L and A in these foci changed for the uniform content of only one marker. Late foci of altered hepatocytes were characterized by a heterogeneous distribution of the markers. 12-14 weeks after the treatment the neoplastic nodules with different antigenic phenotypes dependent on the morphological structure were detected. Cells in neoplastic nodules were uniform as to the marker content. Alpha-fetoprotein was unavailable in foci of altered cells and in neoplastic nodules either. It is concluded that evolution of most of foci follows the way of postnatal maturation similar to that in the normal liver and neoplastic nodules represent a side branch of differentiation blocked at different stages.