SUPPLEMENTARY:
Electron micrograph of a cilium (TS)

Cilia are only found in the respiratory and reproductive systems. They are minute projections (6-7m in length) which arise from the surface of specialised cells. In life, cilia exhibit rapid back and forward movements which are coordinated to propel fluids in one direction. ATP is required as a source of energy for this movement and mitochondria are abundant in the apical cytoplasm of ciliated cells. The transverse section shown here demonstrates the charactaristic 9+2 organisation of the microtubules in the cytoskeleton in an individual cilium.

In the respiratory system the co-ordinated movement of cilia is responsible for transporting the carpet of mucus, produced by the goblet cells and submucosal glands, upwards towards the larynx where the mucus is swallowed.

Paralysis or loss of co-ordination of their activity will lead to a build up of mucus within the respiratory system. Defects in the ultrastructure of the cilium (e.g. Kartagener's syndrome) can lead to severe, chronic lung infections since it allows stagnation of mucus in the lungs. What other problems do you think would be associated with this condition?

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EM of cilia (TS) pathological increase in goblet cells metaplasia of the respiratory epithelium
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