Fig. 4.

Spindle assembly via facilitated Search and Capture. (A) Positioning of the duplicated centrosomes on the shorter axis prior to NEB facilitates rapid formation of nascent spindle and maximal exposure of kinetochores to microtubules at the onset of spindle assembly. (B) Lateral interactions between spindle microtubules and enlarged kinetochores orient centromeres roughly parallel to the spindle axis while nucleation of non-centrosomal microtubules near centromeres promotes capture of microtubule plus ends. (C) Capture of astral microtubules by enlarged kinetochores aligned on the spindle surface ensures rapid formation of direct connections between kinetochores and spindle poles (green arrows). Nascent K-fibers produced by the kinetochores are transported poleward by dynein-mediated gliding astral microtubules (orange arrows). (D) Concerted action of multiple mechanisms results in rapid formation of amphitelic connections (black lines).