Long ducts of collecting tubules extend from

Options

A. cortex to inner part of medulla
B. medulla to outer cortex
C. medulla to inner cortex
D. cortex to outer part of medulla.

Explanation

To solve the question regarding the long ducts of collecting tubules, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of the Kidney**:
- The kidney has two main regions: the outer cortex and the inner medulla. The cortex is the outer layer, while the medulla is the inner layer that contains the renal pyramids.

2. **Identify the Function of Collecting Tubules**:
- Collecting tubules are part of the nephron and are responsible for transporting urine from the nephron to the renal pelvis. They play a crucial role in the final concentration of urine.

3. **Determine the Pathway of Collecting Tubules**:
- The collecting tubules begin in the cortex of the kidney and extend down into the medulla. They collect urine from the nephrons and transport it towards the renal pelvis.

4. **Analyze the Options Given**:
- A. Cortex to inner part of medulla
- B. Medulla to outer cortex
- C. Medulla to inner cortex
- D. Cortex to outer part of medulla

5. **Select the Correct Option**:
- Based on the understanding that the collecting tubules extend from the cortex down into the inner part of the medulla, the correct answer is **Option A: Cortex to inner part of medulla**.

### Final Answer:
The long ducts of collecting tubules extend from the **Cortex to inner part of medulla** (Option A).

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