Anaphase lag describes a delayed movement during anaphase, where one homologous chromosome in meiosis or one chromatid in mitosis fails to connect to the spindle apparatus, or is tardily drawn to its pole and fails to be included in the reforming nucleus. Instead, the chromosome forms a micronucleus in the cytoplasm and is lost from the cell. The lagging chromosome is not incorporated into the nucleus of one of the daughter cells, resulting in one normal daughter cell and one with monosomy. Anaphase lag is one of several causes of aneuploidy and one of several causes of mosaicism. Anaphase lag can also cause a rescue of the daughter cell if the cell was originally trisomy.
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