Mitosis, Light micrograph. The cell at right is in interphase, the stage between mitotic (nuclear) divisions. The cell at left is in prophase, the first stage of mitosis. Mitosis is the formation of two daughter nuclei from one parent nucleus. During interphase the chromosomes, which are made of deoxyribonucleic acid (DNA, dark), are contained within the cell nucleus (round). Interphase is a period of cell growth and synthesis of new organelles. During prophase the chromosomes, which contain 2 identical chromatids, condense into defined units, allowing organised and equal segregation into daughter cells. Magnification: x3500 when printed 10 centimetres across.