Effect of a Carcinogen, 3'-Methyl-4-Dimethylaminoazobenzene on Histopathological Changes of the Liver in Rats Experimentally Infected with Clonorchis sinensis

Wistar rats were used and divided into 3 groups ; group I treated with 0.03% 3'MeDAB alone far 12 weeks, group II given 50 Clonorchis metacercariae alone and group III given 50 metacercariae at the beginning of the treatment with 0.03% 3'MeDAB for 12 weeks. Three rats from each group were examined at 4 week interval up to 40 weeks. For histopathological examination hematoxylin-eosin stain was applied and for ultrastructoral examination electron microscope was used.

In light microscopic examination, nuclear enlargement and hyperchromasia, and nucleolar enlargement were noted in all groups. In group II cell cord disarray, focal necrosis and inflammatory cell infiltration were observed in the later stage. Beside those findings, in group III pseudolobular formation, and cirrhotic changes were demonstrated, and findings of well differentiated hepatocellular carcinoma composed of hyperchromatic and dendritic hepatocytes were evidenced in a case for the first time at the 36th week, then appeared in 2 cases at the 40th week.

In electron microscopic examination nuclear and nucleolar enlargement together with proliferation of rough endoplasmic reticulum and mitochondria were common findings, mild in group I, moderate in group II and marked in group III, in general. With the lapse of time, groupI demonstrated some additional pictures such as clumps of nucleolar chromatin, double nuclei,multiple nucleoli, electron dense granules and nucleolar margination, and group III revealed much more outstanding features such as prominent nucleolar modification, cytoplasmic pseudoinclusion in nucleus, increased free ribosomes and seperation or focal interruption of outer nuclear membrane.