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In genetics, a mosaic or mosaicism denotes the presence of two or more populations of cells with different genotypes in one individual who has developed from a single fertilized egg. Mosaicism can result from various mechanisms including chromosome non-disjunction, anaphase lag and endoreplication. Anaphase lagging appears to be the main process by which mosaicism arises in the preimplantation embryo.〔 Mosaicism may also result from a mutation during development which is propagated to only a subset of the adult cells. Mosaics may be contrasted with chimerism, in which two or more genotypes arise from the fusion of more than one fertilized zygote in the early stages of embryonic development. Mosaicism has been reported to be present in as high as 70% of cleavage stage embryos and 90% of blastocyst-stage embryos derived from in vitro fertilization.〔 ==Types== Different types of mosaicism exist, such as gonadal mosaicism (restricted to the gametes) or tissue or somatic mosaicism. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Mosaic (genetics)」の詳細全文を読む スポンサード リンク
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