Induction of micronuclei in the mouse

The early effects of X-rays, vincristine, cyclophosphamide, quinacrine dihydrochloride, cycloheximide, actinomycin D and hydroxyurea on the induction of micronuclei in mouse bone-marrow erythrocytes were studied. A significant increase in the incidence of micronuclei in polychromatic erythrocytes was seen as early as 5 h after a single treatment with vincristine, 6 h after treatment with X-rays and 10 h after treatment with cyclophosphamide. The cell kinetics of the mouse erythropoietic system described by Cole et al. (1981) can be modified to fit these results. According to this revised model, the final mitosis takes place only 5 h before the expulsion of the nucleus.