A centriole in biology is a hollow cylindrical organelle found in most animal cells, and cells of fungi and algae though not frequently in plants. The walls of each centriole are composed of nine triplets of microtubules, each arranged at a right angle such that when looking down the tube, one end of the triplet pair points slightly outwards and the other end points slightly inwards.
In animal cells as well as certain algae and fungi, there exists a pair of centrioles arranged perpendicularly to each other; these are known as diplosomes, and the region they are located in (close to the nucleus) is known as the centrosome.
Centrioles are important in the cell division process, organizing the spindle upon which the chromosomes are pulled apart. Some animal cells may be able to separate without centrioles. Centrioles assist the cell through the process of mitosis.