[Pathological mitoses in clones of the RA-2 subline of rat transplantable rhabdomyosarcoma selected for increased and decreased frequencies of the formation of spontaneous micronuclei].

Cell substrains with increased and decreased spontaneous levels of micronuclei have been obtained by artificial selection. Clones of the substrains were investigated for mitotic division fidelity. About 200 mitoses were investigated in each clone. Frequencies of mitotic abnormalities such as ana- and telophases with bridge, chromosome and fragment delays at ana- and telophases, scattered chromosomes, chromosomes dislocated from spindle at metaphases and tripolar ana- and telophases were significantly higher in substrains with increased level of micronuclei. This finding indicates that reasons for arising of spontaneous micronuclei and alterations in mitotic division fidelity are the same or closely related. These reasons can be amplified as a result of the artificial selection.