Fig. 6.

Formation of interpolar microtubule bundles. a Microtubules grow from the two spindle poles in arbitrary directions (arrows), eventually approach each other and form interpolar bundles with the help of crosslinking proteins. b Microtubules rotate around the spindle pole (arrows), which allows them to explore the space more efficiently and approach the microtubules extending from the opposite pole more quickly. c Microtubules extending from the opposite poles are connected by minus end directed motors (small black cherry-like object), which align the two microtubules (curved arrow) as they walk towards the spindle pole (straight arrow). In all panels, microtubules are shown as green lines, and centrosomes as green circles with small cylinders representing centrioles