Two counter-current systems are formed in the kidney by ………… and the …………. and respectively.

Explanation

To answer the question regarding the two counter-current systems formed in the kidney, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Counter-Current Mechanism**:
- The counter-current mechanism is a process that allows for the concentration of urine in the kidneys. It involves two structures that work in opposition to each other to maximize the reabsorption of water and salts.

2. **Identifying the Structures**:
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