Abstract

Experimental induction of hyperplastic hepatic nodules was carried out by administration of p-dimethylaminoazobenzene in rats, to correlate with hepatic megalocytosis and to clarify sequence of precancerous lesion. Hyperplastic hepatic nodules and megalocytosis were induced in most of rats following administration of p-DAB : megalocytosis developed during the initial phase (before the 12th wk) of carcinogenesis, and showed a tendency to spread panlobularly from periportal distribution. Those paralleled with increase of compensatory mitotic index following hepatic cell damages by ingestion of p-DAB. Megalocytic index diminished during the phase of hyperplastic nodules and hepatocellular carcinomas, and illustrated no direct relationship with carcinogenesis. Number of hyperplastic nodules regressed with prolongation of experimental duration after cessation of administrating p-DAB. There was a strong evidence to indicate that megalocytosis and compensatory proliferation of hepatocytes would preceed in the p-DAB induced hepatic carcinogenesis and the latter only undergoes into precancerous phase of hyperplastic hepatic nodule.