[Formation of the population composition of a stationary cell culture and the participation of nonproliferating cells with a doubled DNA content in regulating its density]. / Formirovanie populiatsionnogo sostava statsionarnoi kletochnoi kul'tury i uchastie neproliferiruiushchikh kletok s udvoennym soderzhaniem DNK v reguliatsii ee plotnosti.

The conditions of the cultivation of chick embryo diploid cells were alternated (prolonged maintenance with or without medium replacement, with or without consequent cell replating in fresh medium). In different times of culture growth, the cell DNA content was assessed by cytophotometry; the percentage of non-labeled mitoses after incubating the cells with 3H-thymidine and colcemide, as well as the cell density were determined. The phenomenon, detected earlier, of the accumulation of cells containing 4c DNA during the transition of the culture from logarithmic into the stationary phase of growth, was confirmed. These cells were shown to differ in their ability to survive in conditions of stationary culture and by proliferative potential. The fraction of cells reversibly arrested in G2-period was described, by which fraction the change of the cell population size is occurring after the decrease of its proliferation rate. The transitional stage is distinguished at the beginning of the stationary phase of culture growth. During this stage the stabilization of structural and numerical composition of the population is taking place.

[Accumulation of nonproliferating cells containing 4c DNA in stationary diploid cell cultures]. / Nakoplenie neproliferiruiushchikh kletok, soderzhashchikh 4c DNK, v statsionarnykh kul'turakh diploidnykh kletok.

The cell proliferation was stimulated in stationary cultures of chick and human embryo cells by changing the medium. The cumulative indices of labeled cells and labeled mitosis as well as the cellular DNA contents were determined in the stimulated cultures at different times of growth until their entry into the stationary phase of growth. It is established that in the case of mass entry of cells into DNA synthesis period, part of them does not complete the mitotic cycle to be arrested in the G2-period. This arrest is considered as one of the ways of the cell proliferation inhibition in cultures entering into the stationary phase.