What is G0 (quiescent phase) of cell cycle?

G0 or quiescent phase is the stage wherein cells remain metabolically active, but do not proliferate unless called to do so. Such cells are used for replacing the cells lost during injury.

Quiescent Stage (G₀): Cells which do not divide further, exit G₁ phase to enter an inactive stage. This stage is called quiescent stage (G₀) of the cell cycle. The cells in this stage remain metabolically active but do not undergo division. But these cells can resume division as and when required.

Some cells in the adult animals do not appear to exhibit division (e.g., heart cells and many other cells divide only occasionally, as needed to replace cells that have been lost because of injury or cell death.

These cells do not divide further exit G₁ phase to enter an inactive stage called quiescent stage (G₀) of the cell cycle. Cells in this stage remain metabolically active but no longer proliferate unless called on to do so depending on the requirement of the organism.