Cytologic changes induced in rat livers cells by short-term exposure to chemical substances.

All the hepatocarcinogens administered to rats markedly increased the mitotic rate in the liver. Except for alpha-benzene hexachloride and nitrosobutylurea, the nonhepatocarcinogens did not appreciably increase the mitotic rate. Cytogenetic analyses on the ploidy rate and chromosome abnormalities evidence qualitative differnces among mitotic liver cells in animals treated with hepatocarcinogens and chromosome changes in liver cells observed after the administration of hepatocarcinogenic substances may have some relation to an essential process in hepatocarcinogenesis.