Synchronized Chinese hamster cells in vitro were used to examine the stage dependence of the induction of polyploidy by X-irradiation. The data obtained from various experiments, including cells that were in the G1 and S stages of the cell cycle only, showed that polyploid cells can be induced only when they are irradiated in G1. This finding is supported by autoradiographic studies, in which no induced polyploid cells were labeled with <tex-math>${}^{3}{\rm HTdR}$</tex-math>, and by the fact that chromosome aberrations were observed only in these polyploid cells.

This content is only available as a PDF.
You do not currently have access to this content.