Classification of Flagella by Lateral Appendages

Classification of Flagella by Lateral Appendages

Beyond the shared internal 9+2 axoneme, flagella can differ considerably in their external appearance, particularly in whether and how they bear fine, hair-like lateral outgrowths called mastigonemes along the length of the flagellar shaft. This variation is used to classify flagella into five recognised types:

• Stichonematic — a flagellum bearing a single row of lateral mastigonemes running along one side of the shaft.
• Pantonematic — a flagellum bearing lateral mastigonemes arranged in two rows, on opposite sides of the shaft (giving the flagellum a feather-like appearance).
• Acronematic — a flagellum that is smooth along most of its length but bears a single, fine, whip-like terminal filament at its very tip.
• Pantacronematic — a flagellum combining both features: lateral mastigonemes along the shaft (as in the pantonematic type) together with a fine terminal filament at the tip (as in the acronematic type).
• Anematic — a flagellum that is entirely smooth, lacking lateral mastigonemes of any kind along its shaft. …