The in vitro micronucleus assay and kinetochore staining: methodology and criteria for the accurate assessment of genotoxicity and cytotoxicity.

The in vitro micronucleus assay is currently one of the most commonly used test systems for the study of genotoxic effects of chemicals. It is considered the preferred method for measuring chromosome damage as it allows the determination of both chromosomal loss and breakage. The type of chromosomal damage induced can be distinguished by using the kinetochore or pan-centromeric staining using molecular probes that label the centromeric regions of chromosomes allowing the determination of aneugenic (chromosome loss) or clastogenic (chromosome breakage) agents. In this chapter, we provide a description of the basic principles and methods of the in vitro micronucleus assay with detailed explanations of the scoring criteria for the genotoxicity and cytotoxicity end-points by manual or automated analysis.