Heterochromatin and chromosomal aberration in microtus agrestis: role of chromosomal association

Mitomycin C (MC) -induced chromatid aberrations among the chromosomes of Microtus agrestis are preferentially localized in the constitutive heterochromatic regions, i.e., major part of the sex chromosomes and the centromeric regions of the autosomes. In the sex chromosomes, intrachanges predominate, while interchanges between the two X chromosomes are very rare. This pattern of distribution of different types of aberrations is interpreted as due to the individual chromocentres that are formed by the two X chromosomes in the interphase.