The karyotypic structure of cell populations in vitro as an integral system.

This review describes regularities of karyotypic variability maintaining karyotypic stabilization of continuous cell lines. Statistical analysis of individual karyotypes of "marker" and "markerless" cell lines show that survival of cell population in vitro is maintained by a certain ratio of cells with different structural variants of karyotype (SVK). Characteristic feature of karyotypic variability in the "markerless" cell lines during long-term cultivation under various conditions is dicentric formation due to telomeric associations. These dicentrics seem to form genetical structures providing adaptation to conditions in vitro of the cell population as an autonomous system. Correlations between the numerical variability reflecting in SVK, and structural variability (dicentric formation) are manifestations of an integral cell-populational function. Experimental data allow to suggest that integrity of the karyotypic structure of cell populations is maintained not only by selection of random variations, but also by programmed (adaptive) changes of karyotype. As a whole, in the cell population the state is realized that can be called karyotypic homeostasis; the observed phenomena characterize processes maintaining such homeostasis.