Which of the following is absent in the walls of veins ?

Options

A. Smooth muscles
B. Outer elastic lamina
C. lnner elastic lamina
D. Tunica adventitia

Answer

To solve the question "Which of the following is absent in the walls of veins?", we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of Veins**:
- Veins have three main layers in their walls:
- **Tunica Externa (Adventitia)**: The outermost layer.
- **Tunica Media**: The middle layer, which contains smooth muscle.
- **Tunica Interna (Intima)**: The innermost layer.

2. **Identify the Components of Each Layer**:
- **Tunica Externa**: This layer is primarily made of connective tissue and may contain some elastic fibers.
- **Tunica Media**: This layer contains smooth muscle fibers, which help in the contraction and dilation of the vein.
- **Tunica Interna**: This layer is lined with endothelial cells and may have some elastic fibers.

3. **Examine the Options Given**:
- The options typically include:
- Smooth muscles
- Outer elastic lamina
- Inner elastic lamina
- Tunica adventitia (another name for tunica externa)

4. **Determine Which Component is Absent**:
- **Smooth Muscles**: Present in the tunica media.
- **Outer Elastic Lamina**: Present in the tunica externa.
- **Inner Elastic Lamina**: This is typically absent in veins. It is more commonly found in arteries.
- **Tunica Adventitia**: This is another term for the tunica externa and is present.

5. **Conclusion**:
- The component that is absent in the walls of veins is the **Inner Elastic Lamina**.

### Final Answer:
The correct answer is **Inner Elastic Lamina**.

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