Poleward kinetochore fiber movement occurs during both metaphase and anaphase-A in newt lung cell mitosis

Fluorescence photoactivation demonstrated the movements of kinetochore fiber microtubules during metaphase and anaphase. Kinetochore microtubules were suggested to altertheir length through polymerization and depolymerization at the kinetochores during the two particular phases of mitosis. This occurence transpired as the kinetochores migrated toward and backward the poles. Only depolymerization was believed to be possible at the pole during the two mitotic stages. The results implied that two molecular processes influences the poleward force production for migration of chromosomes.