Arrangement of Ciliary Microtubules

The arrangement of ciliary microtubules refers to the organization of microtubules within cilia and flagella. The correct arrangement is crucial for the proper functioning of these cellular structures.

Option B: 9 2

In the 9+2 arrangement, the cilia and flagella have a central pair of microtubules surrounded by 9 outer doublets. This arrangement provides structural support and allows for movement through the coordinated sliding of microtubules.

9 Doublets
- The outer ring of ciliary microtubules consists of 9 doublets, each doublet composed of a complete A-tubule and an incomplete B-tubule.
- These doublets provide stability and structure to the cilia or flagella.

2 Central Microtubules
- In the center of the cilia or flagella, there are 2 microtubules that are not part of the doublet structure.
- These central microtubules play a role in regulating the movement and beating pattern of cilia and flagella.

Function
- The 9+2 arrangement of ciliary microtubules is essential for the motility of cilia and flagella.
- The sliding of microtubules against each other powered by dynein arms allows for the characteristic wave-like motion of cilia and flagella, enabling their role in movement and cellular processes.

In conclusion, the 9+2 arrangement of ciliary microtubules is a fundamental structural feature that underlies the function of cilia and flagella in various organisms.