motile cilia

The architecture of the microtubule backbone distinguishes motile cilia, in which nine doublets of microtubules surround a central pair (9+2), from primary cilia, in which the central pair of microtubules is absent (9+0).

Function

Motile cilia and flagella appeared very early in evolution to provide unicellular organisms with motility in water. Adaptation to non-aquatic life in plants resulted in the almost complete elimination of these organelles, except for gametic transport in some phylogenetic groups.

In contrast, cilia and flagella were retained and employed for a wide variety of functions requiring fluid movement in complex multicellular animals.

The function of the primary cilium as a highly conserved sensory organelle in evolution. The functions of cilia in diverse processes such as left-right axis pattern formation, cerebrospinal fluid flow, - sensory reception, mucociliary clearance and renal physiology indicate that cilia have been adapted as versatile tools for many biological processes.

Pathology

 primary ciliary dyskinesia

• Kartagener syndrome
• situs inversus totalis (MIM.270100)

 Bardet-Bield symdrome
 ADPKD

See also: stereocilia

References

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