Studies on Culture Lines Derived from Mouse Liver Parenchymatous Cells Grown in Long-Term Tissue Culture

The characteristic morphology of NCTC strain 721 from mouse liver epithelium and the strains derived from it as NCTC clone 1469 and NCTC strain 1795 tissue-cultured cells has been described. No apparent difference among the three strains is distinguishable. Strain 721 tissue-cultured cells still continue to produce no tumors upon injection into C3H mice, even though efforts have been made to obtain tumors through the use of x-radiated mice as hosts. Clone 1469 tissue-cultured cells developed from strain 721 cells have, over a period of years, produced two tumors in 142 x-radiated mice. Strain 1795 cells in vitro developed from one of these two tumors, however, had a 53 per cent tumor incidence in nonirradiated mice and a 66 per cent incidence in x-radiated mice. Tumors arising from 1795 tissue-cultured cells were transplantable. The histologic pattern of the tumors from NCTC clone 1469 and NCTC strain 1795 appeared to be similar irrespective of whether the tumor arose in nonirradiated or x-radiated mice. The histology of these tumors suggested that they are hepatomas.