Propagation of L strain mouse cells in suspension

A technique is described for cultivating Earle's L strain mouse cells in suspension in a chemically defined solution supplemented with horse serum. The increase in population density was about 1.3 × 10 6 cells per ml during the logarithmic phase if the medium was not renewed. The generation time was about 28 hours. Renewal of the medium at suitable intervals permitted the population to increase exponentially to a density of 5 × 10 6 cells per ml. L cells could be kept indefinitely in the logarithmic phase by frequent subculture. Dialysed horse serum added to the defined solution supported cell multiplication as well as an equal amount of undialysed serum. If either methionine or glucose was omitted from the medium containing dialysed serum no cell proliferation occurred. During the logarithmic phase of multiplication the amounts of RNA, DNA and protein per cell remained constant.