Collecting tubes or ducts combine to form

Options

A. Duct of Bellini
B. Bidder's canal
C. Columns of Bertin
D. Ureter

Answer

To solve the question "Collecting tubes or ducts combine to form," we need to analyze the options provided and identify which structure is formed by the combination of collecting tubes or ducts.

### Step-by-Step Solution:

1. **Understanding Collecting Ducts**:
- Collecting ducts are the final segments of the nephron in the kidney. They play a crucial role in the reabsorption of water and the concentration of urine.

2. **Analyzing the Options**:
- **A. Duct of Bellini**: This is also known as the papillary duct. It is formed by the convergence of several collecting ducts and is responsible for transporting urine from the renal pyramids to the renal pelvis.
- **B. Betis Canal**: This structure is found in frogs and is involved in the reproductive system, receiving sperm from the testes. It is not related to the collecting ducts in humans.
- **C. Column of Bertin**: This refers to the renal cortex's medullary extension and is not formed from collecting ducts. It is present between renal pyramids and serves as an anchorage.
- **D. Ureter**: This is the tube that carries urine from the kidney to the bladder, but it is not formed directly from the collecting ducts.

3. **Identifying the Correct Answer**:
- The option that directly corresponds to the combination of collecting ducts is **A. Duct of Bellini**. This structure is indeed formed by the merging of multiple collecting ducts.

4. **Conclusion**:
- Therefore, the correct answer to the question is **Duct of Bellini**.

### Final Answer:
**Duct of Bellini**