Appearance of intestinal type of tumor cells in hepatoma tissue induced by 3'-methyl-4-dimethylaminoazobenzene.

Carcinoma tissues induced by 3'-methyl-4-dimethylaminoazobenzene were investigated both morphologically and biochemically. The most prominent histological pattern was an undifferentiated carcinomatous one. While this type of carcinoma, histologically, appeared to be due to a uniform population of cells, electron microscopic examination revealed that the carcinoma tissue was composed of many types of cells including cells that contained either the brush border or the mucous droplets seen in goblet cells. In addition, tumor cells that contain serotonin-like granules were noticed. An electrophoretogram of alkaline phosphatase in the tissue extract of this type of carcinoma revealed distinctly the presence of its intestinal isozyme. These findings evidently show that carcinoma induced by 3'-methyl-4-dimethylaminoazobenzene includes in addition to the cells differentiated toward hepatocytes or cholangiolar cells, those differentiated toward intestinal epithelial cells.