AP BIOLOGY

Detailed explanation-1: -During cellular cleavage, the contractile ring tightens around the cytoplasm of the cell until the cytoplasm is pinched into two daughter cells. During the final phase of mitosis, telophase, the furrow forms an intercellular bridge using mitotic spindle fibers.

Detailed explanation-2: -During cytokinesis, the cleavage furrow appears suddenly on the surface of the cell and deepens rapidly (Figure 18-30). Because the cytoplasm is clear, the spindle can be observed in real time through a microscope.

Detailed explanation-3: -At this point, the cell membrane fuses shut on either side of the contractile ring – creating the membranes of two new and independent cells. Cleavage furrows are primarily found in animal cells and some algal cells.