[Exponential growth status of the cell number. I. The independence of the portion of proliferating cells found in different phases of the mitotic cycle from the variability in phase durations].

A mathematical model of the cell tumour kinetics has been analysed for a population being characterized with the exponential growth of the cell number, the absence of cell losses, and the proliferative pool Pc less than or equal to 1. It is shown that the values of part of proliferative cells, being in one phase of the mitotic cycle, do not depend on the kind of cell distribution function in respect to the phase duration. A graphic method is proposed for the estimation of the proliferative pool, the mean mitotic duration and the doubling time of the cell number, provided we know the mitotic, index, the index of the phase S, and the mean durations of mitotic cycle, of mitosis and of phase S.