Figure 18-10. The three classes of microtubules of the fully formed mitotic spindle in an animal cell.

Figure 18-10The three classes of microtubules of the fully formed mitotic spindle in an animal cell

(A) In reality, the chromosomes are proportionally much larger than shown in this drawing, and multiple microtubules are attached to each kinetochore. Note that the plus ends of the microtubules project away from the centrosomes, while the minus ends are anchored at the spindle poles. Although the centrosomes initiate the assembly of the spindle poles, most of the kinetochore and overlap microtubules that they nucleate are released from the centrosomes and are then held and organized at the poles by motor proteins. For simplicity, in the other figures in this chapter, we draw all the spindle microtubules at the poles emanating from the centrosomes. (B) A phase-contrast micrograph of an isolated mitotic spindle at metaphase, with the chromosomes aligned at the spindle equator. (B, from E.D. Salmon and R.R. Segall, J. Cell Biol. 86:355–365, 1980. © The Rockefeller University Press.)

From: Mitosis

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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