The frequency of chromosomal aberrations in long-term irradiated mice and rats.

The frequency of chromosomal aberrations was studied in myelokaryocytes of mice and rats continuously irradiated for 90 days at a dose rate of 50R/day. The curves expressing the frequency of chromosomal aberrations in continuously irradiated mice and rats are biphasic. The first phase is similar for the two species and is characterized by an increase in the frequency of cells with chromosomal aberrations. In the second phase, the frequency of cells with chromosomal aberrations had stabilized at a level of 25--28% in rats, and in mice the values of aberrant cells were gradually increasing until the end of irradiation when they reached 40.1%. In contrast to it, the distribution of aberrations of the chromatid and chromosomal types did not change throughout the experiment in both animal species.