G0 Phase

Many differentiated cells normally do not leave the G0 phase. They can only reenter the cell cycle in the case of special events (injury, cell loss). The nerve cells are an exception; they can no longer divide (regenerate) and therefore remain permanently in the G0 phase. Cells in the G0 phase are not divisible, but metabolically very active. If necessary, some of the cells can re-enter the cell division cycle at any time. Reentry into the cell division cycle is controlled by growth factors, which in turn are influenced by regulatory genes.