Centrioles are cylindrical bodies composed of nine sets of triplet microtubules. They occur in pairs (diplosomes) near the center of the cell and are oriented with their long axes at right angles to each other. They measure about 150 nm in diameter and 300-500 nm in length. Centrioles play a key role in cellular division and are capable of reproducing themselves as well as producing structurally identical basal bodies which form the base of cilia. Centrioles are absent from some highly-differentiated cells such as neurons and cardiac muscle cells which consequently lose the ability to reproduce.
