[Chromosome bridges and tailed nuclei in malignant cell populations]

Cell clones of the finite organospecific rat rhabdomyosarcoma RA-23 were selected in vivo for high and low frequency of interphase cells with chromosome bridges. After selection for high frequency of cells with bridges, the frequency of cells with anomalies of nuclear form sharply increased in the cell populations. These anomalies were manifested by long nuclear protrusions into the cytoplasm. This type of anomaly was termed tailed nuclei. In the studies populations of RA-23, the frequency of cells with "tailed" nuclei positively correlates with the frequency of interphase cells with chromosome bridges and the frequency of ana- and telophases with chromosome bridges. These parameters might be genetically associated: dicentric chromosomes form chromosome bridges in ana- and telophases of mitosis. Then, in some cases, the bridges are maintained, which result in the appearance of interphase cells with bridges, and, in other cases, the bridges are ruptured, which result in the appearance of cells with tailed nuclei.