Mitosis. Transmission electron micrograph showing mitosis, metaphase in a gut epithelial cell. Mitosis, the usual method of cell division, characterized typically by the resolving of the chromatin of the nucleus into a threadlike form, which condenses into chromosomes, each of which separates longitudinally into two parts, one part of each chromosome being retained in each of two new cells resulting from the original cell. The four main phases of mitosis are prophase, metaphase, anaphase, and telophase. Mitochondria are in yellow and cell nuclei purple. Magnification: 5000x when printed 10 centimetres across.