[The dependence of the incidence of encountering cells with micronuclei in the experimental metastases of rat rhabdomyosarcoma on the duration of the growth and on the size of these metastases].

Cell suspensions of rat transplantable rhabdomyosarcoma RA-2 were injected to white rats. The experimentally induced lung metastases (ELM) were estimated according to the frequency of micronucleated cells (MNC) that appeared 9-20 days after injection (a. i.). The frequency of MNC in ELM decreased from 2.7% (9 days a. i.) to 0.7% (20 days a. i.). The ELM which were of the same size but were examined at different time after injection had equal frequencies of MNC. At each investigated time after injection the least frequencies of MNC were observed in the ELV of the biggest size. The data provided allow to infer that the growth time and site of ELM may influence the spontaneous karyotype instability rates.