Kinetic analysis of cell population growth during culturing in vitro

XL-2 cells (Xenopus laevis) were used for kinetic analysis of cell populati on growth. The dependence of the time of cell duplication on the percentage of cells in G(0) phase of the cell cycle was studied and described by the mathematics formula. Possible causes of changes in the ratio between the percentage contents of cells in the cell cycle and those in G(0) phase were analyzed. They are: de crease in the percentage of cells in G(0) phase because of increase in the number of dividing cell, position in the cell island, quantity of nuclei, i nterdisposition of cells in G(0) phase. It was shown that loosing of free e dge by cells during their transition to the second layer of the cell island without changes in spreading, led to a significant increase in the percent age content of cells in G(0) phase. The percentage of cells in G(0) phase i ncreased about 5 times for multinuclear cells. Analysis of position of cell s in G(0) phase showed that majority of these cells were placed in groups o f 2, 3 or 4 cells. Studies of the real cell culture in the logarithmic phase of growth 48-120 h of culturing showed that the percentage of cells in G(0) phase did not vi rtually changed - all processes were equalized by each other. We propose a new method for defining the cell cycle duration under conditio ns from the time of the cell culture duplication and the data on the percen tage content of cells in G(0) phase. This method can be used, when traditio nal approaches using BrdU or [H-3]thymidine are difficult or unacceptable.