In Vivo Rodent Micronucleus Test (OECD 474) Screening and Regulatory Support The micronucleus test (MNT) is used to determine if a compound is genotoxic by evaluating the presence of micronuclei. Micronuclei may contain chromosome fragments produced from DNA breakage (clastogens) or whole chromosomes produced by disruption of the mitotic apparatus (aneugens). Male and/or female rats or mice are treated with the test compound at three dose levels, usually two or three times at 24-hour intervals. Approximately 24 hours after the last dose, bone marrow or peripheral blood is collected to determine the frequency of micronucleated polychromatic erythrocytes (MN-PCEs) or micronucleated reticulocytes (MN-RETs), respectively. A positive outcome is characterized by a statistically significant, dose-dependent increase in MN-PCEs or MN-RETs that exceeds historical control limits. Can be combined with standard toxicology tests, the comet assay and the Pig-a assay. Administration routes include: oral, intravenous, infusion and inhalation When to Perform Screening Abbreviated formats available or can be added to non-GLP tolerability studies IND-enabling As part of the ICH S2(R1) standard battery (Option 1 or 2) REACH requirement To follow up a positive result in any of the Annex VII or VIII genotoxicity tests You may also be interested in... REACH Services Drawing on our REACH compliance experience, we offer a full range of services to meet the requirements of REACH. Build a Customized IND Gantt Chart Our interactive tool provides you with an estimated timeline to help you better plan your IND program.