Differential interference contrast (DIC) light micrograph of onion (Allium cepa) meristematic cells undergoing mitosis (nuclear division). Mitosis is the formation of two daughter nuclei from one parent nucleus. Some of the cells are in the anaphase stage of mitosis. At anaphase sister chromatids, which are made of DNA (deoxyribonucleic acid, red), are moved to separate poles by spindles (not seen). Two identical chromatids make up one chromosome, so each cell retains a copy of the parent cell's genetic information. Other cells are in telophase, the last stage of mitosis before cytokinesis (cellular division). Orcein staining.