[Colony size spectra of 60Co-gamma-irridiated CHO fibroblasts following freeze and thaw cycles].

The production of reproductive lethal cell lesions by freeze and thaw cycles has been studied by means of colony size spectrometry in tetraploid CHO-fibroblastoma protected with glycerine. The verification sensitivity of this method is compared with that of the colony formation test, the survival curve of cells and the relative multiplicity. 20 days after a freeze and thaw cycle only the spectrometry of the colony size and survival curve of the cells and colonies suggest a cell lesion. After 44 days, changes as a consequence of reproductive lethal lesions can be detected only in the spectrum of the colony size. Survival curves of the colonies, survival curves of the cells and relative multiplicities determined on cell strains 44 days after a freeze and thaw cycle are not significatively different from the results of non-frozen control cells. The relation of the average cellular multiplicity after a freeze and thaw cycle to that of the nonfrozen control cells approaches the value of 1 with increased cultivation period after a freeze and thaw cycle. The reproductive lethal lesion after a freeze and thaw cycle is also decreasing with an increased cultivation period. Proliferation lesions by means of 60-Co gamma irradiation have been influenced in dependence of the dose by 20 days of freeze and thaw lesions of a cell population.