Relationship of Contact Inhibition to Tumor Transplantability, Morphology, and Growth Rate1

Summary Sublines of BHK21 hamster cells were derived by treatment with 5-fluoro-2′-deoxyuridine. These sublines demonstrated increased contact inhibition in vitro . The tumors resulting from injection of these sublines were examined, and cells from the tumors were returned to culture. Sublines with increased contact inhibition were less efficient at initiating tumors. All tumors, however, had an identical morphology and pattern of growth. Although contact inhibition in vitro was inversely correlated with capacity for initiation of in vivo growth, it did not affect morphology or pattern of tumor growth. After growth as solid tumors, cells returned to culture were found to retain their original degree of contact inhibition, indicating that passage through the animal had not led to selection of a common transplantable cell type.