Skip to main content
. Author manuscript; available in PMC: 2018 Sep 1.
Published in final edited form as: Nat Rev Mol Cell Biol. 2017 Jul 12;18(9):533–547. doi: 10.1038/nrm.2017.60

Figure 1. Structures and functions of motile and non-motile cilia.

Figure 1

All cilia extend from a basal body that typically consists of triplet microtubules, and subdistal and distal appendages. Distal appendages (also known as transition fibres) tether the basal body to the base of the ciliary membrane. Immediately distal to the basal body is the transition zone, which contains doublet microtubules that are connected to the ciliary membrane via Y-shaped structures. Axonemes (the ciliary backbone) are composed of doublet microtubules. In motile cilia, axonemes usually contain associated structures and proteins (for example, the central pair and axonemal dyneins) that are required for ciliary motility. Nodal cilia are an exception as they are motile but lack a central pair of microtubules. Cilia may contain additional subdomains, including singlet microtubules at the distal end, and regions with specific protein compositions or functions (for example, the inversin domain (INV; involved in signalling). Key cell signalling functions and roles in motility are summarized. PKD, polycystin.