ABSTRACT
In the course of two chronic experiments including the administration of N-2-acetylaminofluorene (N-A-AF) to male Wistar rats, alterations were observed in the fine structure of the nuclei isolated from the liver. After the first 3 to 4 months of ingestion of the carcinogen, the heterochromatin became uniformly distributed throughout the nucleus, with dissociation of the nucleolus-associated heterochromatin. At longer intervals (7 months) evidence was found in the nucleus of various types of inclusions, chiefly granular virus-like bodies. Subsequently, the frequency of inclusions diminished but the liver cell nucleus remained large, with numerous large nucleoli. This suggested the existence of a stage of metabolic activation of the liver cell nucleus in the course of experimental induction of hepatocarcinoma with N-A-AF, giving rise to an increase in the nuclear and nucleolar volume by accumulation of synthesis products and disorders in nucleo-cytoplasmic exchanges.
