Human chromosomes in metaphase. The chromatin is stained red and the "glue" that holds the two chromatids together is highlighted in yellow. This glue is a proteinaceous complex called cohesin. Once all the chromosomes are attached to the spindle, the cohesin complex breaks down, allowing the two chromatids to separate and move to opposite poles of the cell.

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Credit: Human chromosomes in metaphase. The chromatin is stained red and the "glue" that holds the two chromatids together is highlighted in yellow. This glue is a proteinaceous complex called cohesin. Once all the chromosomes are attached to the spindle, the cohesin complex breaks down, allowing the two chromatids to separate and move to opposite poles of the cell. Matthew Daniels. Source: Wellcome Collection.