CHAPTER 8. Micronuclei in the Bone Marrow Cells of Rodents

The micronucleus assay is one of the genotoxicity assays used to detect chromosomal aberration induction in vivo. Rodent micronucleus assay using erythropoietic cells has been used most widely for chemical safety in the risk assessment of human health. In this chapter, we will discuss the mechanism of micronucleus formation from chromosomal aberrations, methodology of the assay, evaluation and interpretation of the assay results, modification of the standard assay, namely in target tissues other than the bone marrow, and automation of the assay. We mainly provide rationale for why the rodent micronucleus assay is widely used for regulatory purposes rather than describing the usual textbook or standard operation procedure. We also discuss how to evaluate the assay results and how to interpret the data to determine the human risk of the test chemical.