The layer of basement membrane which lies close to the epithelial cells is  

Options

A. Basal lamina
B. Reticular lamina
C. Endothelium
D. Mesothelium

Answer

To solve the question regarding the layer of the basement membrane that lies close to the epithelial cells, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of the Basement Membrane**: The basement membrane is a thin, fibrous layer that separates epithelial cells from the underlying connective tissue. It consists of two main layers: the basal lamina and the reticular lamina.

2. **Identify the Layers**:
- **Basal Lamina**: This is the layer of the basement membrane that is closest to the epithelial cells. It is primarily composed of collagen and glycoproteins and serves as a foundation for the epithelial cells.
- **Reticular Lamina**: This layer lies beneath the basal lamina and is made up of a network of reticular fibers. It provides structural support but is not in direct contact with the epithelial cells.

3. **Evaluate the Options**:
- **Endothelium**: This refers to the thin layer of cells lining blood vessels and is not part of the basement membrane.
- **Mesothelium**: This is the layer of cells that line body cavities and is also not part of the basement membrane.
- **Basal Lamina**: This is the correct answer as it is the layer that lies closest to the epithelial cells.
- **Reticular Lamina**: This is further away from the epithelial cells and is not the correct answer.

4. **Conclusion**: Based on the definitions and the structural organization, the layer of the basement membrane that lies close to the epithelial cells is the **Basal Lamina**.

### Final Answer:
The layer of basement membrane which lies close to the epithelial cells is the **Basal Lamina**.

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