Cilia and flagella construction

Cilia and flagella are constructed from a complex array of microtubules whose organisation is different along their length. The basal body sits in the cytoplasm of the cell and tethers and nucleates the axoneme through a region called the transitional zone. Whereas the top of the basal body has nine pairs of triplets the axoneme has nine pairs of doublets and two central MTs which are not linked. This arrangement is crucial for bending of the axoneme. Over 200 other proteins make up cilia and flagella and most of their functions are still not known.