In Vitro Mammalian Cell Micronucleus Test (OECD 487) Screening and Regulatory Support The mammalian cell micronucleus test (MNT) is used to determine if a compound is genotoxic to cells in culture 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). The test can be performed in primary human peripheral blood lymphocytes (HPBLs) or established cell lines, such as Chinese hamster ovary (CHO) or TK6 cells. Cultures are incubated with several concentrations of the test compound for three to four hours in the presence and absence of metabolic activation (S9) and for 21 to 24 hours in the absence of S9. A positive outcome is characterized by a statistically significant, dose-dependent increase in micronucleated cells that exceeds historical negative control limits. Continue the Conversation » When to Perform Screening IND-enabling As part of the ICH S2(R1) standard battery REACH requirement As part of Annex VIII testing You may also be interested in... Build a Customized IND Gantt Chart Our interactive tool provides you with an estimated timeline to help you better plan your IND program. In Vitro Services These services support metabolic, toxicokinetic and bioanalytical investigations with both qualitative and quantitative data. REACH Services Drawing on our REACH compliance experience, Charles River offers a full range of services to meet the requirements of REACH.