Intracellular cations and basophilia in rat liver parenchyma during azo dye carcinogenesis.

Following formation of hyperplastic nodules, some areas of presumptive preneoplastic liver parenchyma show intense cytoplasmic RNA staining. This hyperbasophilia is not associated with increased ribosome content. Histochemical localization of metallic cations remaining after Carnoy fixation implies an inverse relationship with toluidine blue staining. In liver tissue fixed with potassium pyroantimonate, more inorganic cation precipitation occurs in nucleic of hyperbasophilic foci and hepatomas than within surrounding liver parenchyma. Electron microscopic observations of hyperbasophilic hepatocytes revealed large deposits of cation antimonate within nucleoli and nuclear interchromatin areas and finer deposits in apparent association with cytoplasmic ribosomes. Thus, differences in basophilia may reflect variations in cation levles. Since hyperbasophilic foci show increased thymidine incorporation, cell proliferation may be correlated with histochemically detected alterations of intracellular cations.