Experimental hepatocellular carcinogenesis.

The sequential development of lesions in the liver leading to hepatocellular carcinoma in experimental animals appears to follow a similar pattern irrespective of the carcinogen. The speed with which the lesions develop is related to the chemical, the dose and dosing schedule, and the diet fed. In studies with aflatoxin B1 there is a predictable series of morphological expressions beginning with focal areas of hydropic degeneration (Stage 1); hyperplastic basophilic cells, singly or in close association with Stage 1 (Stage 2); nodular hyperplasia of parenchymal cells which become progressively more abnormal (Stage 3); transitional cell changes (Stage 4); and, ultimatley, hepatocellular carcinoma (Stage 5).