PATHOLOGY

Detailed explanation-1: -The contractile ring shrinks at the equator of the cell, pinching the plasma membrane inward, and forming what is called a cleavage furrow. Eventually, the contractile ring shrinks to the point that there are two separate cells each bound by its own plasma membrane.

Detailed explanation-2: -Formed during cytokinesis, the last step of cell division, the contractile ring is composed of filamentous actin (F-actin) and the motor protein myosin-2, along with additional structural and regulatory proteins.

Detailed explanation-3: -Animal cell cleavage furrow formation is caused by a ring of actin microfilaments called the contractile ring, which forms during early anaphase. Myosin is present in the region of the contractile ring as concentrated microfilaments and actin filaments are predominant in this region.

Detailed explanation-4: -Cytokinesis is the final act of cell division. In a typical animal mitosis, a cleavage furrow forms at the equatorial cortex after anaphase. This furrow then advances inwards to separate the two daughter cells.

Detailed explanation-5: -Microtubules may regulate cleavage by sending out ‘signals’ that induce contractile ring formation, regulate contractility and direct membrane traffic. Other cell types use other spatial cues.