Micronucleus test
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A micronucleus test is a test used in toxicological screening for potential genotoxic compounds. There are two major versions of this test, one in vivo and the other In vitro. The in vivo test normally uses mouse bone marrow or mouse peripheral blood. Micronuclei were first used to quantify chromosomal damage by H.J. Evans et al., in roottips of the Broad Bean, Vicia faba. Subsequently the in vivo assay was developed independently by W. Schmid and by J.A. Heddle and their colleagues. The assay is now recognized as one of the most successful and reliable assays for genotoxic carcinogens, i.e., carcinogens that act by causing genetic damage. The mouse peripheral blood assay was developed by J.T. MacGregor and has now been adapted for measurement by flow cytometry by A. Tometsko and colleagues. The first use of micronuclei in cultured cells was by J.A. Heddle and colleagues in human lymphocytes. The assay has been improved by M. Fenech and colleagues for use in lymphocytes and other cells in culture cells.
A micronucleus is the erratic (third) nucleus that is formed during the anaphase of mitosis or meiosis.
Using fluorescent in situ hybridization (FISH) with probes targeted to the centromere region, it can be determined if a whole chromosome, or only a fragment is lost.
