Differential interference contrast (DIC) light micrograph of onion (Allium cepa) meristematic cells in the prometaphase (left) and metaphase (right) stages of mitosis (nuclear division). Mitosis is the formation of two daughter nuclei from one parent nucleus. At prometaphase the chromatin has condensed but there is not yet complete attachment of the chromosomes to the spindle. At metaphase sister chromatids, which are made of DNA (deoxyribonucleic acid, red), line up along the centre of a cell. During the next stage, anaphase, the chromatids are separated to opposite ends of the cell. Two identical chromatids make up one chromosome, so each cell retains a copy of the parent cell's genetic information. Orcein staining.