Symptoms of X-Ray Damage to Radiosensitive Mouse Leukemic Cells: Asynchronous Populations

The extreme X-ray sensitivity of the L5178Y S/S cell line is described in terms of cytological symptoms associated with its radiation-induced death. As such, this study forms part of a continuing series of experiments attempting to understand the radiosensitivity of the murine leukemic lymphoblast line. Symptoms of X-ray damage occurred in far more exaggerated forms than those displayed by other mammalian cell types, including a long mitotic delay of approximately 10 hr after a dose of 100 rads and a very high incidence of multipolar postirradiation divisions. Fluorometric profiles indicate that the cells spend the long delay in the <tex-math>${\rm G}_{2}+{\rm M}$</tex-math> phase of the cell cycle. Cellular protein contents and volumes continue to increase during that time. The low survival of L5178Y S/S cells after irradiation may be related more to faulty cytokineses than to chromosomal aberrations per se.