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Abstract

Abbreviations: MNCs, micronucleated cells; MNi, micronu-clei; N/C ratios, nuclear-cytoplasmic ratios; MN/PN ratios, ratio between area of micronucleus (MN) to the parent nucleus (PN) IntroductionMicronucleus (MN) is a microscopically visible, small, round or oval, non-refractive extra-nuclear cytoplasmic chromatin mass which consists of eccentric chromosomes or chromosomal fragments, originated either from aberrant mitosis or due to genotoxicity and completely detached from the parent nucleus (PN) of the respective somatic cell. MN is small, incomplete and originates either from the laggard chromosome or its fragment due to partial impairment of the spindle apparatus during anaphase. In the course of telophase, such chromatin material might be included into one or the other daughter cell, where it can either fuse with the main nucleus or form one or several secondary nuclei.1 The formation of MN in dividing cells is the result of chromosome breakage due to unrepaired or mis-repaired DNA lesions, or chromosome malsegregation due to mitotic malfunction. These events may be induced by oxidative stress, exposure to clastogens or aneugens, genetic defects in cell cycle checkpoint and/or DNA repair genes, as well as deficiencies in nutrients required as cofactors in DNA metabolism and chromosome segregation machinery. MN is surrounded by double membranes, and contains chromosomes or fragments of chromosomes which have not been incorporated into one of the daughter nuclei during cell division. 3,4Conflicting opinions related to the size of micronuclei (MNi) still exist in literature. The relative sizes of the MN are reported to be approximately 1/5 th to 1/3 rd area of the PN.The cell bearing one or multiple number of micronuclei (MNi) is known as micronucleated cell (MNC). Appearance of MNCs due to potential carcinogens and environmental mutagens has been shown to be a reliable and sensitive biomarker for cytogenetic damage.5 Among a number of tests, the micronucleus test (MNT) has been implicated both for in vivo and in vitro cytogenetic analysis to indicate chromosomal aberrations.6,7 Application of the MNT in exfoliated buccal cells is an innovative genotoxicity technique, which holds promise for the study of epithelial carcinogens. Micronuclei are suitable internal dosimeters for revealing tissue-specific genotoxic damage in individuals exposed to carcinogenic mixtures. [8][9][10] Almost all the papers published so far are based on either mutagenicity or carcinogenicity of MNCs and none of these was reported on its pathogenicity. Therefore, the objectives of the present study are to evaluate the frequency and pathogenicity of such oral MNCs with respect to age, sex and site through cytodiagnostic approach and to bring about a comprehensive conflict resolution on size of the MNi in oral MNCs through morphometric analysis. MethodologyThe subjects AbstractObjective: Micronucleated cells (MNCs) are a special type of cytological atypia observed in the exfoliated cytosmears of control and oral neoplasm cases. Conflicti...