By Levi Clancy for Student Reader on
Microtubule organizing centers (aka centrosomes) are composed of asters at each end, with centrosomes spanning between them. The tubules that connect to the chromosome kinetochore are called kinetochore microtubules, while the tubules which interact with each other are polar microtubules (aka non-kinetochore microtubules). Microtubules are composed of α- and β-tubulin monomers polymerized to form hollow tubes. Depolymerization shortens the microtubules, while the chromosomes simultaneously migrate toward the asters, driving apart the spindle poles.