Give an account of the ultra structure of an axoneme.

Explanation

Ultra structure of flagellum : The axial filament or axoneme shows 9+2 organisation under the electron microscope. Two central singlets are enclosed by fibrous inner sheath. Nine peripheral doublets form a cylinder between inner sheath and outer sheath. The "A" microtubule of each doublet is connected to the inner sheath by radial spokes. It also has pairs of arms all. along the length and are directed towards the neighbouring doublet. These arms are made of a protein called dyenin. These arms create the sliding force. The peripheral doublets are surrounded by an outer membranous sheath called protoplasmic sheath, which is the extension of.plasma membrane. Some flagella bear lateral appendages called flimmers or mastigonemes along the length of.the axoneme above the level of pellicle.
Each flagellum arises from a basal granule that lies below the cell surface in the ectoplasm.