[Possible mechanisms of the emergence of chromosome rearrangements. VI. Mitotic delay as a protective mechanism. Origin of spontaneous chromosome breaks].

It was proved by the investigation of the bone marrow cells and the culture of embryonic fibroblasts of mice, that experimental induction of chromosome breaks having such a distinctive feature as disposition of acentrics outside the equatorial plate at metaphase, results in reduction of the mitotic index and the radiation induced structural mutations frequency. Such disposition of acentrics--outside the equatorial plate--is typical for spontaneous chromosome breaks. It was suggested, that the process resulting in spontaneous chromosome breaks is a component of the protective mechanism, which is put into effect through the mitotic delay.