Final answer:
Microtubules reorganize around the centrosome during mitosis to form the mitotic spindle which is essential for chromosome segregation.
Step-by-step explanation:
As cells enter mitosis, their microtubules disassemble and then reassemble to form the mitotic spindle, with a focus at the centrosome, a special animal cell microtubule organizing structure. The centrosome is composed of two centrioles which serve as the origin points from which microtubules extend. During prophase, microtubules emanate from each centrosome as it migrates to opposite sides of the cell. These microtubules assemble into the spindle apparatus that is crucial for chromosome segregation during cell division.