Apparent species restriction in the isolation of proliferating embryonal carcinoma cell hybrids

Proliferating somatic cell hybrids are readily obtained from the fusion of a metabolic co-operation-defective mouse embryonal carcinoma cell variant (R5/3) to LMTK- (1 fibroblastic mouse line derived from L-M) and to derivatives of the R5/3 parental cell line PC13. However it has not yet proved possible to produce growing hybrids from fusions between R5/3 and any non-mouse cell line. It appears, from both this work and that of others that although polyethylene glycol-induced fusion occurs between embryonal carcinoma cells and other cell types viable hybrids cannot always be isolated.