The authors studied growth peculiarities of the ascitic hepatoma 22A at the terminal stage of development. As shown by the autoradiography method, some of the cells could be at the G1-period or at the R1-period for 2 or even 4 days; the average duration of the G2-period constituted 16 hours. 55--60% of the cells were at the much prolonged G1- and R1-period, 7%--at the S-period, and 9%--at the G2-period. The rest 25--30% of cells apparently leave the mitotic cycle irreversibly since they take no part in proliferation after the division stimulation.
Animals Cell Cycle