Mitosis

Prophase
Chromatin condenses to form chromosomes. Centrioles migrate to opposite poles of the cells (except in plant cells which do not have centrioles). Microtubules develop and form a star shaped structure known as an aster, and spindle fibres may develop. Nucleolus disappears, and the nuclear membrane disintegrates.

Metaphase
During this phase, the chromosomes arrange themselves at the equator of the cell, and they are attached to the spindle fibres at the centromere. Each chromosome is still composed of two chromatids.

Anaphase
During this phase, each centromere duplicates and the spindle fibres contract or shorten further. This causes the chromatids of each chromosome to separate and migrate to opposite poles, led by the centromeres. The shortening of the spindle fibres is due to the progressive removal of the tubulin molecules of which they are made.

Telophase
Chromatids reach their respective poles and a new nuclear envelope forms around each group. Chromatids uncoil and lengthen. The spindle fibres disintegrate and a nucleolus reforms again in each nucleus. A new cell membrane is formed. In the case of plants, a new cell wall also forms.

Cytokinesis subsequently occurs.