In the axoneme of cilium, the pair of central microtubules are connected to peripheral microtubules (doublet) by

Options

A. Axial spoke
B. Radial spoke
C. Linkers
D. Inter doublet bridge

Answer

To solve the question regarding the connection between the central microtubules and the peripheral microtubules (doublets) in the axoneme of a cilium, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of Axoneme**:
- The axoneme is the structural core of cilia and flagella, consisting of microtubules arranged in a specific pattern. It typically has a "9+2" arrangement, which means there are 9 peripheral doublets of microtubules surrounding 2 central microtubules.

2. **Identify the Types of Connections**:
- In the axoneme, the central microtubules are connected to the peripheral doublets. The question asks for the specific type of connection between these structures.

3. **Analyze the Options Provided**:
- The options given are:
- A) Axial spoke
- B) Radial spoke
- C) Linkers
- D) Inter-doublet bridge

4. **Evaluate Each Option**:
- **Axial Spoke**: This term is not commonly used in the context of cilia structure.
- **Radial Spoke**: This is a known structure that connects the peripheral doublets to the central microtubules. It plays a crucial role in the stability and function of the axoneme.
- **Linkers**: This term can refer to various connecting proteins, but it does not specifically describe the connection in question.
- **Inter-Doublet Bridge**: This refers to connections between the peripheral doublets themselves, not to the central microtubules.

5. **Select the Correct Answer**:
- Based on the analysis, the correct answer is **B) Radial spoke**, as it specifically describes the structure that connects the central microtubules to the peripheral doublets in the axoneme.

### Final Answer:
The pair of central microtubules in the axoneme of a cilium are connected to the peripheral microtubules (doublets) by **radial spokes**.

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