The spindle apparatus, or simply the spindle, is a network of microtubules (also called "spindle fibers") that forms within a dividing eukaryotic cell, both during mitosis and meiosis (see figure at right). Some of these microtubules attach to the cell walls, others attach to individual chromosomes at their kinetochores.
It's the spindle that pulls the chromosomes from the metaphase plate to the poles. The radiating microtubules of the spindle form asters (see figure left) — aster is Greek for star. The two points where the spindle fibers converge are the centrosomes.
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Dividing human cell: chromosomes in blue, kinetochores in
red, and spindle in green. The hairlike green strands are
microtubules.
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