The mucosal lining of which organ differs from others in concerned with the number of layers of the cell (simple/startifide):

Options

A. Stomach
B. Small intestine
C. PCT
D. Oesophagus

Answer

To solve the question regarding the mucosal lining of which organ differs from others in terms of the number of layers of cells (simple or stratified), we can analyze each of the given options step by step.

### Step-by-Step Solution:

1. **Identify the Organs**: The options provided are the stomach, small intestine, proximal convoluted tubule (PCT), and esophagus.

2. **Examine the Stomach**: The stomach is lined with a simple columnar epithelium. This type of epithelium consists of a single layer of tall, column-like cells, which are specialized for secretion (e.g., gastric juices) and absorption. Therefore, the stomach does not have a stratified epithelium.

3. **Examine the Small Intestine**: Similar to the stomach, the small intestine is also lined with simple columnar epithelium. This epithelium is adapted for absorption of nutrients and does not have multiple layers. Thus, the small intestine does not have a stratified epithelium either.

4. **Examine the Proximal Convoluted Tubule (PCT)**: The PCT in the nephron of the kidney is lined with cuboidal epithelium. This epithelium consists of a single layer of cube-shaped cells and is involved in the reabsorption of water and nutrients. Therefore, the PCT does not have a stratified epithelium.

5. **Examine the Esophagus**: The esophagus is lined with stratified squamous epithelium. This type of epithelium consists of multiple layers of flat cells, which provide protection against mechanical stress and abrasion as food passes through. The stratified nature of this epithelium is crucial for its protective function.

6. **Conclusion**: Among the given options, the esophagus is the only organ that has a stratified epithelium, while the others (stomach, small intestine, and PCT) have simple epithelium.

### Final Answer:
The organ whose mucosal lining differs from others in terms of the number of layers of cells is the **esophagus**.