Proliferation kinetics and specific behaviour of G2 cells of the Bp8 mouse ascites sarcoma in vivo.

Growth characteristics of the Bp8 ascites sarcoma were investigated by means of evaluation of total cell number, the cellular DNA content, the mitotic index and the percentage of dead cells. Following intraperitoneal inoculation of 18 x 10(6) cells into NMRI mice a plateau level of about 1400 x 10(6) cells was reached after 7 days followed by a daily decline of 5 per cent up to day 14, the terminal stage of life. Based on the increase of the cell number and the distribution of cells in the cell cycle the flow rate through and the duration of the various parts of the cell cycle were calculated. Generally, the durations of all phases of the cell cycle including mitosis increased with age, most markedly after day 8 when the durations tended to become infinite. At the plateau phase the total number of G1, S-phase and mitotic cells decreased significantly while G2 cells remained at a constant level. This finding may be of interest in view of the concept of ascites tumour cells behaving as a regulated cell system.