Question

Which of the following is correct regarding the structure of a section of cilia/flagella?

• A. Peripheral microtubules(doublets)- 9+0; Central microtubules(singlets)- 2; Radial spokes- 8; Central Sheath- 1
• B. Peripheral microtubules(doublets)- 9+2; Central microtubules(singlets)- 9+0; Radial spokes- 9; Central Sheath- 1
• C. Peripheral microtubules(doublets)- 9; Central microtubules(singlets)- 2; Radial spokes- 9; Central Sheath- 1
• D. Peripheral microtubules(doublets)- 3; Central microtubules(singlets)- 6; Radial spokes- 9; Central Sheath- 1

Answer 1

Answer: (C)

Peripheral microtubules(doublets)- 9; Central microtubules(singlets)- 2; Radial spokes- 9; Central Sheath- 1

The axoneme (core) of cilia and flagella has nine pairs doublets of radially arranged peripheral microtubules, and a pair of centrally located microtubules. The central tubules are connected by bridges and is also enclosed by an central sheath, which is connected to one of the tubules of each peripheral doublets by a radial spoke. There are nine radial spokes.