Microfilaments Microfilaments are solid, rodlike structures composed of actin . They provide structural support, and play a roll in phagocytosis, cell and organelle movement, and cell division . Intermediate filaments are tough fibers made of polypeptides . They help to strengthen the cytoskeleton and stabilize cell shape . Centrioles Centrioles are located near the nucleus and appear as cylindrical structures consisting of a ring of nine evenly spaced bundles of three microtubules .
Centrioles play a role in the formation of cilia and flagella.
During animal cell division , the mitotic spindle forms between centrioles . Both consist of 9 fused pairs of protein microtubules with side arms of the motor molecule dynein that originate from a centriole. This complex of microtubules is surrounded by a sheath continuous with the cytoplasmic membrane. In the presence of ATP, the dynein side arms of the microtubules in the outer ring elongate and attempt to move along the neighboring pair, causing the flagellum or the cilium to bend. Flagella and cilia function in locomotion .