The centrosome is the region in a cell where microtubules are broken down and assembled during cell division. Located alongside the nucleus, the centrosome contains two centrioles. At metaphase, the centrioles separate and the two regions of the centrosome containing them move to opposite sides of the cell as the microtubules form a spindle. The spindle evenly divides the chromosomes into the two daughter cells. See also haploid.