Division Delay in HeLa Cells and Chinese Hamster Cells a Time-lapse Study

Abstract

Division delay after irradiation with ⁶⁰Co was studied in HeLa cells by hourly observations of sister cell pairs, well separated from each other, and in V79-1 hamster cells by time-lapse photomicrography of small colonies. A maximum delay was observed if HeLa cells were irradiated toward the end and hamster cells during the middle of their life cycle. A fraction of the post-irradiated generation of hamster cells were delayed but this was unrelated to the delay in the previous generation. The response of sister cells was then investigated in order to eliminate the stage of development during irradiation as a variable quantity. The results suggest that ‘biologically alike’ cells (i.e. sister cells) may show a variation in their division delay; this delay, however, is modified to approach a common value if the cells remain in proximity. Cell disintegration was found to be more extensive during the post-irradiated generation.