Cilium and flagellum:
(i) Cilia and flagella have fundamentally the same structures. Each cilium or flagellum consists of eleven microtubules.
(ii) These microtubules are arranged in two radii. Of these, nine are doublets. These are situated at the periphery and the remaining two are single microtubules situated in the centre.
(iii) The microtubules are enclosed in a cytoplasmic matrix to form an axial filament.
(iv) The outer tubules are 360 Å in diameter and are composed of two sub-units.
(v) These are found around the cylinder. The central microtubules are enclosed in a common sheath.
(vi) From the centre arise nine secondary filaments These are connected with tubules of the outer doublets.
