Mitosis. Immunofluorescence light micrograph of a cell (centre) in metaphase during mitosis (nuclear division). During mitosis two daughter nuclei are formed from one parent nucleus. At metaphase, the chromosomes (yellow) line up along the centre of the cell, and the spindles (blue) grow from their poles to the centromeres at the centre of each chromosome. Chromosomes are made up of two identical sister chromatids, which are separated into the two daughter nuclei, so that each daughter cell retains the parent cell's genetic information. Spindles are made of microtubules, protein filaments, that are part of the cell's cytoskeleton.