抄録
In the previous paper (Takano et al., 1961), the fundamental behavior of several human cell lines to 60Co γ-irradiation was described on the basis of dose-response curve estimated by the cell population 7 days after irradiation. The human uterus cancer HeLa strain was subjected to irradiation with a dose of 2000r, and surviving cells were grown to form colonies. As the result, a cell group developed with a little increased tendency in radioresistance.
In the present study, the irradiation and cultivation were repeated up to 5 times or 10, 000r in the accumulated dose, and some stable changes in radioresistance and other biological characters of the HeLa cells were revealed to have occurred.
