Studies on the Radiosensitivity of the Chromosomes in Cultured Human Cells

사람의 배양세포염색체의, 방사선감수성에 관한 연구

The present experiment was perform to investigate the frequencies of chromosome aberration with special regard to the chromosome groups and the various time intervals after X-irradiation (60 r) in ormal human foetus cells grown in culture. The cytological preparations were prepared at every 5 through 30 hours after X-irradiation by the air-drying method. 1. The frequencies of chormosome aberration are on the whole decreased as tie elapses after irradiation and this is thought to be due to gradual recovery with time . However, a slight increase in frequencies is observed at 25 and 30 hours after irradiation respectively. This shows that the cells at the these periods are more sensitivity to X-irradation , and those cells are thought to be at G$_2$ and late S stage at the time of irradiation respectively, so t is evident that G$_2$ and late S stages a the time of irradiation respectively , so it is evident that G$_2$ and late S stages are more sensitive to X-irradiation than any other stages. 2. The frequencies of chormosome aberration are decreased in descending order of chormosome group number. The differences among these frequencies are highly significant statistically . Therefore it can be concluded that there is a highly significant difference in radiosensitivity among chromosome groups. that is, the chromosomes of the group A are the most radiosensitive , followed by B, C, D ,E and G in descending order.