Vasa recta is absent or highly reduced in a

Explanation

### Step-by-Step Solution:

1. **Understanding Vasa Recta**: Vasa recta are the straight capillaries that supply blood to the renal medulla. They play a crucial role in the countercurrent exchange mechanism, which is essential for the concentration of urine.

2. **Identifying Nephron Types**: There are two main types of nephrons in the kidney:
- **Cortical Nephrons**: These are located primarily in the renal cortex and have shorter loops of Henle.
- **Juxtamedullary Nephrons**: These are located at the border of the cortex and medulla and have longer loops of Henle that extend deep into the medulla.

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