Abstract: Cilia are located on almost all cell types of the human body, the basic structure includes a microtubule cytoskeleton, the axoneme, and the surrounding ciliary membrane. Cilia perform key tasks for a variety of organs, but defects in the structure or function of them are involved in the pathogenesis of several cilia-related disorders. Mammalian cilia occur in two major pattern: motile 9+2 cilia and usually nonmotile 9+0 primary cilia, which function as a sort of cellular antenna, to pick up signals from the environment and pass them on to the cell's nucleus. Mammalian ciliary beating is regulated by cAMP, cGMP, PKC as well as Ca²⁺ and intracellular pH. To further explore the structure and function of cilia, and the regulation mechanism of mammalian ciliary beat frequency is of great importance for the diagnosis and treatment of certain cilia-related disorders.

Key words: cilia, axoneme, ciliary beat frequency