Ultrastructure of liver tumors induced in F344 rats by methapyrilene.

Liver tumors induced in F344 rats by methapyrilene were studied by electron microscopy. The tumor cells constituting hepatocellular carcinomas showed a pronounced increase in the number of mitochondria and conformational changes of these organelles while the content of lipid, glycogen and smooth endoplasmic reticulum was greatly reduced. The cholangiocarcinomas consisted of bile duct epithelia at varying stages of squamous metaplasia.