[Cytospectrophotometry of hepatocyte RNA in regenerating and neoplastic liver]

The present work consists in a quantitative cytospectrophotometric investigation of the cytoplasmic hyperbasophilia that characterizes the foci of neoplastic transformation and the tumor cells in rats fed hepatocarcinogens. It reveals that the increase in the dye-binding capacity shown by the cytoplasmic RNA of these cell populations results primarily form a qualitative alteration which raises the affinity for basic dyes by a factor of nearly 2, and also to a change in concentration due to volumetric changes which may again double the staining intensity of these hepatocytes. This phenomenon of hyperbasophilia differs radically from the weak variations in basophilia observed in normal regenerating liver and in hyperplastic liver parenchyma of rats fed the carcinogenic diet in which cases the changes appear to be related mainly to de nova RNA synthesis. Biochemical assays on cellular fractions indicate that the ribosomes are the organelles responsible for the hyperbasophilic properties that hepatocytes acquire in areas of neoplastic transformation.