PATHOLOGY

Detailed explanation-1: -After M phase, some cells do not divide further and exist G1 phase to enter an inactive stage called quiescent stages (G0) of the cell cycle. Cells in G0 stage remain metabolically active but no longer proliferate unless called on to do so depending on the requirement of the organism.

Detailed explanation-2: -The cell is in a quiescent (inactive) stage that occurs when cells exit the cell cycle. Some cells enter G0 temporarily until an external signal triggers the onset of G1. Other cells that never or rarely divide, such as mature cardiac muscle and nerve cells, remain in G0 permanently.

Detailed explanation-3: -Cells usually exit the cell cycle in order to differentiate into the distinct cell types of an organism, such as neurons, muscle or fat (Sun and Buttitta, 2017).

Detailed explanation-4: -Some dividing cells exit the cell cycle and enter the vegetative inactive stage. This is called the Quiescent Stage (G0).