Figure 18-31. An experiment demonstrating the influence of the position of microtubule asters on the subsequent plane of cleavage in a large egg cell.

Figure 18-31An experiment demonstrating the influence of the position of microtubule asters on the subsequent plane of cleavage in a large egg cell

If the mitotic spindle is mechanically pushed to one side of the cell with a glass bead, the membrane furrowing is incomplete, failing to occur on the opposite side of the cell. Subsequent cleavages occur not only in the conventional relation to each of the two subsequent mitotic spindles (yellow arrowheads), but also between the two adjacent asters that are not linked by a mitotic spindle—but in this abnormal cell share the same cytoplasm (red arrowhead). Apparently, the contractile ring that produces the cleavage furrow in these cells always forms in the region midway between two asters, suggesting that the asters somehow alter the adjacent region of cell cortex to induce furrow formation between them.

From: Cytokinesis

Cover of Molecular Biology of the Cell
Molecular Biology of the Cell. 4th edition.
Alberts B, Johnson A, Lewis J, et al.
New York: Garland Science; 2002.
Copyright © 2002, Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, and Peter Walter; Copyright © 1983, 1989, 1994, Bruce Alberts, Dennis Bray, Julian Lewis, Martin Raff, Keith Roberts, and James D. Watson .

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