Brush border columnar epithelium is the lining of

Options

A. Stomach
B. Oesophagus
C. Proximal convoluted tubules
D. Small intestine

Answer

**Step-by-Step Solution:**

1. **Understanding Brush Border Columnar Epithelium**: The term "brush border columnar epithelium" refers to a specific type of epithelial tissue that has microvilli on its surface. These microvilli increase the surface area for absorption.

2. **Identifying the Function of Microvilli**: Microvilli are tiny, finger-like projections that enhance the absorptive capacity of the epithelial cells. They are primarily involved in the absorption of nutrients.

3. **Analyzing the Options**:
- **Stomach**: The stomach is lined with a different type of epithelium (simple columnar epithelium) that does not have microvilli.
- **Esophagus**: The esophagus is lined with stratified squamous epithelium, which is also not the brush border type.
- **Proximal Convoluted Tubule**: This part of the kidney does have brush border epithelium, but it is not primarily known for this feature.
- **Small Intestine**: The small intestine is lined with brush border columnar epithelium, which has microvilli that play a crucial role in nutrient absorption.

4. **Conclusion**: Based on the analysis, the correct answer to the question "Brush border columnar epithelium is the lining of?" is the **small intestine**.

---