[Dynamics of changes in a population of human fibroblasts after long-term cultivation in the stationary phase].

Defined and repeated alterations in human fibroblasts were discovered under continuous cultivation in the stationary phase. In the normal diploid fibroblast population, two cell subpopulations were distinguished by the heterochromatinization degree of the nucleus. While in the stationary phase, the number of cells with a parahaploid number of large chromocenters, regularly arranged in the nucleus, is seen increasing. It is supposed that the death of the normal diploid fibroblast culture occurs primarily at the expence of cells with heterochromatinized nuclei. Examination of strains with trisomy (47, XY, +7) and of a strain taken from a patient with pigmented xeroderma has shown that the process of nucleus heterochromatinization and its dynamics are substrains. A possibility is discussed of gene or chromosome mutation influences on the well-regulated nuclear heterochromatinization process and on the cell population structure alteration.