A fascinating and dynamic component of the cytoskeleton, microtubules are hollow cylindars composed of the protein tubulin. Within the cell, microtubules are organized by a structure known as the centrosome. A centrosome consists of two orthogonally oriented centrioles surrounded by associated proteins. With a few exceptions in the cells of certain organisms, the walls of a centriole are composed of nine triplets of microtubules.

In addition to their central role in the structures of cilia and flagella, they also associate with dyneins and kinesins for the intracellular transport of vesicles and other organelles. Additionally, microtubles make up spindle apparati that segragate the chromosomes in mitosis and meiosis.