Effects of Irradiation on the Cell Cycle of an Experimental Ascites Tumour of the Mouse

SummaryThe parameters of growth kinetics of an experimental ascites tumour were measured at different times after irradiation with 250 rads. These parameters were studied in young, fast-growing tumours and in older, slow-growing tumoursAfter irradiation, the duration of G2 is lengthened in the old tumours and unchanged in the young ones. In the younger tumours, there is an accumulation of cells in G1, whereas in the cell cycle is lengthened after irradiation in the young tumours, but this effect seems to be reversible. It seems also lengthened in the old tumours, but it is impossible with our data to calculate in this case the duration of the cell cycle.