[Preliminary studies of the relationship between micronucleus formation and cell cycle]

For the study of the relationship between micronucleus formation and chromosome aberration. Lymphocytes of human peripheral blood were treated with MMC and chromosome aberrations and micronuclei which produced at various phases of cell cycle were observed. For the study of the main results are as follows: (1) the MMC induced increase in the frequency of aberration cells at metaphase (ACF), that of the frequency of micronucleated cells at G1, S and G2 phases (cultured in vitro, C-MNCF) and that of the frequency of micronucleated cells at G0 phase (Non-cultured, NC-MNCF) are all dose-dependent and their dose-response relation can be described by power regression; (2) the MMC-induced micronucleus formation at G0 phase is not related to chromosome aberration, but the change of NC-MNCF is positively related to the change of CAF as same as C-MNCF; (3) the MMC-induced MNCFs detected in binucleated cells by the cytokinesis block method increase slightly as compared with C-MNCFs, and the ratio of MNCF/ACF is less (about 0.1) and decreases along with the increase of MMC concentrations. The results suggest that the relationship between micronucleus formation and chromosome aberration may be quite complex, that chromosome aberration could be one of the cause of micronucleus formation.