MICRONUCLEUS TEST AND METAPHASE ANALYSES IN MICE EXPOSED TO KNOWN ANDSUSPECTED SPINDLE POISONS

Micronucleus (Mn) and metaphase chromosome analyses were performed in mouse bone marrow cells with two known and eight suspected mitotic spi ndle poisons. Polychromatic (PCEs) and normochromatic (NCEs) erythrocy tes were scored for presence of Mn, while structural (CAs) and numeric al chromosome aberrations (NCAs), i.e. hyperploid cells, were evaluate d by metaphase analysis. CAs were scored in first, and NCAs in the sec ond metaphases, identified by BrdUrd differential staining. Hydroquino ne induced Mn, NCAs and CAs; colchicine, vinblastine and, to a lesser extent, chloral hydrate, diazepam and econazole induced both Mn and NC As; cadmium chloride and thimerosal induced Mn and CAs, while pyrimeth amine and thiabendazole induced Mn only. The proposed stepwise protoco l allowed satisfactory statistical evaluation of the effects induced w ith a reduction in the number of animals killed. An acceptable agreeme nt was found between induction of Mn and NCAs, suggesting a possible u se of the Mn test for revealing compounds with aneugenic properties.