Phase contrast light micrograph of an onion (Allium cepa) meristematic cell in the prophase stage of mitosis (nuclear division). Mitosis is the formation of two daughter nuclei from one parent nucleus. At prophase the nuclear envelope dissolves and the chromosomes (red) condense. During mitosis 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.