Abstract

: A "micronucleus" is a small nucleus. The nucleus is the organelle in the cell that contains the genetic material (DNA) that directs normal cellular function and cellular reproduction. In cells of eukaryotic organisms, the nucleus contains DNA packaged into chromosomes. In vivo mutagencity and carcinogenicity studies are posing a high demand for test related resources. The in vitro micronucleus assay is a mutagenic test system for the detection of chemicals which induce the formation of small membrane bound DNA fragments i.e. micronuclei in the cytoplasm of interphase cells. These micronuclei may originate from acentric fragments (chromosome fragments lacking a centromere) or whole chromosomes which are unable to migrate with the rest of the chromosomes during the anaphase of cell division. The micronucleus assay is an important component of genetic toxicology screening programs. There is substantial evidence that chromosome mutations and related events in oncogenes and tumor suppressor genes of somatic cells are involved in induction and/or progression of some cancers in humans and experimental animals. The study of DNA damage at the chromosome level is an essential part of genetic toxicology because chromosomal mutation is an important event in carcinogenesis. The micronucleus assays have emerged as one of the preferred methods for assessing chromosome damage because they enable both chromosome loss and chromosome breakage to be measured reliably

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