The structure of which of the following consist of a layer of single cell thickness

Options

A. Blood capillary
B. Artery
C. Venule
D. arteriole

Answer

To determine which structure consists of a layer of single cell thickness, we need to analyze the options provided: blood capillary, artery, venule, and arteriole.

### Step-by-Step Solution:

1. **Understand the Question**: We need to identify which of the given structures has a wall that is only one cell thick.

2. **Analyze Each Option**:
- **Artery**: Arteries have thick muscular walls to withstand high blood pressure and control blood flow. Therefore, they do not consist of a single cell layer.
- **Venule**: While venules are smaller blood vessels that collect blood from capillaries, they still have walls that are thicker than a single cell layer.
- **Arteriole**: Arterioles also have muscular walls to regulate blood flow, similar to arteries, and are not a single cell thick.
- **Blood Capillary**: Blood capillaries are specifically designed for the exchange of gases and nutrients. They consist of a wall that is only one cell thick (endothelial cells), allowing for efficient exchange between blood and tissues.

3. **Conclusion**: The structure that consists of a layer of single cell thickness is the **blood capillary**.

### Final Answer:
The structure that consists of a layer of single cell thickness is the **blood capillary**.

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