<P> Microtubule - organizing centers function as the site where microtubule formation begins, as well as a location where free - ends of microtubules attract to . Within the cells, microtubule - organizing centers can take on many different forms . An array of microtubules can arrange themselves in a pinwheel structure to form the basal bodies, which can lead to the formation of microtubule arrays in the cytoplasm or the 9 + 2 axoneme . Other arrangements range from fungi spindle pole bodies to the eukaryotic chromosomal kinetochores (flat, laminated plaques). MTOCs can be freely dispersed throughout the cytoplasm or centrally localized as foci . The most notable MTOCs are the centrosome at interphase and the mitotic spindle poles . </P> <P> Centrioles can act as markers for MTOCs in the cell . If they are freely distributed in the cytoplasm, centrioles can gather during differentiation to become MTOCs . They can also be focused around a centrosome as a single MTOC, though centrosomes can work as an MTOC absent of centrioles . </P> <P> Most animal cells have one MTOC during interphase, usually located near the nucleus, and generally associated closely with the Golgi apparatus . The MTOC is made up of a pair of centrioles at its center, and is surrounded by pericentriolar material (PCM) that is important for microtubule nucleation . Microtubules are anchored at the MTOC by their minus ends, while their plus ends continue to grow into the cell periphery . The polarity of the microtubules is important for cellular transport, as the motor proteins kinesin and dynein typically move preferentially in the "plus" and "minus" directions respectively, along a microtubule, allowing vesicles to be directed to or from the endoplasmic reticulum and Golgi apparatus . Particularly for the Golgi apparatus, structures associated with the apparatus travel towards the minus end of a microtubule and aid in the overall structure and site of the Golgi in the cell . </P> <P> Movements of the microtubules are based on the actions of the centrosome . Each daughter cell after the cessation of mitosis contains one primary MTOC . Before cell division begins, the interphase MTOC replicates to form two distinct MTOCs (now typically referred to as centrosomes). During cell division, these centrosomes move to opposite ends of the cell and nucleate microtubules to help form the mitotic / meiotic spindle . If the MTOC does not replicate, the spindle cannot form, and mitosis ceases prematurely . </P>

Where are centrosomes (microtubule-organizing-centers) located in an animal cell