HISTOCHEMICAL DIFFERENCES BETWEEN SO-CALLED MEGALOCYTOSIS AND NEOPLASTIC OR PRENEOPLASTIC LIVER-LESIONS INDUCED BY N-NITROSOMORPHOLINE

Differences in histochemical pattern were found between the so-called megalocytes and preneoplastic and neoplastic hepatocytes after short-term administration of sublethal dose of N-nitrosomorpholine in rats. Megalocytes were poor in glycogen and intensely pyroninophilic. The activity of alkaline and acid nucleases was normal or increased. On the other hand the clear and acidophilic hepatocytes considered to be preneoplastic showed excessive storage of glycogen and had usually decreased or absent activity of nucleases. Basophilic cells of neoplastic nodules and hepatocellular carcinomas were practically free from glycogen and nuclease activity. The majority of megalocytes which disturbed seriously the lobular architecture of liver during the NNM intoxication, disappeared soon after the withdrawal of carcinogen. The megalocytes are interpreted as the result of an interaction between toxic and regenerative events. © 1979.