Animals and many unicellular organisms have hollow and cylindrical organelles known as centrioles.

Formation of centrioles:

They are made up of nine triplets of microtubules that are composed of an important protein known as, tubulin. Animal cells have two centrioles located near the exterior surface of the nucleus. The two centrioles are collectively called centrosomes.

The function of centrioles:

Their function is to help in the formation of spindle fibers during cell division. In cells that contain cilia and flagella, centrioles are involved in the formation of cilia and flagella.