Metaphase PtK1 cell microinjected with X-rhodamine-labeled tubulin and Alexa 488-labeled CENP-F antibodies, to fluorescently label kinetochore fibers (red) and kinetochores/spindle poles (green), respectively.
The movie shows that sister kinetochore pairs oscillate between the two spindle poles as their respective kinetochore fibers lengthen and shorten.

Digital images were acquired every 20-60 seconds at a 60X magnification. Elapsed time is shown in min:sec