what anchors the spindle

The spindle apparatus is the cytoskeletal structure of eukaryotic cells that forms during cell division to separate sister chromatids between daughter cells. The spindle fibers move chromatids around during cell division, and the centrioles anchor them. The kinetochore also serves as an anchor, allowing the spindle fibers to retract and separate the sister chromatids. The spindle apparatus includes spindle microtubules, associated proteins, which include kinesin and dynein molecular motors, condensed chromosomes, and any centrosomes or asters that may be present at the spindle poles depending on the cell type. The spindle apparatus is vaguely ellipsoid in cross-section and tapers at the ends. In the wide middle portion, known as the spindle midzone, antiparallel microtubules are bundled by kinesins. At the pointed ends, known as spindle poles, microtubules are nucleated by the centrosomes in most animal cells.