|Components of a centrosome (Image: Wikimedia)|
Centrioles are present within the centrosomes of animal cells, as well as in the cells of some fungi, in green algae, and in such plants as liverworts, mosses, hornworts, and ferns (seed plants, however, lack them). They are cylindrical structures, each made up of nine microtubule triplets (see figure at right), and are present as pairs within each centrosome, where they lie at right angles to each other, forming a T-shape. They replicate at the same time as the centrosome and serve as a center for the assembly of the spindle apparatus during cell division during both mitosis and meiosis.
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