[Relationship between oval cells and preneoplastic lesions induced by 2-acetylaminofluorene in rat liver].

OBJECTIVE

To study the cellular origin of preneoplastic lesion of liver induced by the 2-acetylaminofluorene (2-AAF) in rat.

METHODS

Male fisher 344 rats were used for two different carcinogenesis models. Model 1: Rats were fed with regular diet containing 0.02% 2-AAF for totally 28 days, and subjected to a standard two thirds partial hepatectomy (2/3 PH) on the 7th day in order to stimulate the proliferation of oval cells. 3H thymidine (3H-Tdr) was administered intraperitoneally on the 12th day for selective labelling of oval cells. Model II: Rats were subjected to 2/3 PH and 3H-Tdr was administered intraperitoneally 22 hours after the operation for the selective labelling of hepatocytes. The rats were then fed with 2-AAF for totally 28 days after a 9 days recovery period from 2/3 PH. The relationship between preneoplastic lesion and selectively labelled oval cells, or hepatocytes, was traced by autoradiography.

RESULTS

Pathological examination and autoradiography denoted that the silver grains (labelled signals) were only formed in the preneoplastic cells in model I rather than the cells of model II animals.

CONCLUSION

It is a direct evidence to demonstrate that the preneoplastic cells are mostly originated from the oval cells.