Which of the following statement is not true about nephrons ?

Options

A. Cortical nephrons are more common.
B. Cortical nephrons lack vasa recta
C. In Juxta medullary nephrons, the blood first passes through vasa recta and then through the capillaries of glomerulus.
D. The glomeruli of Juxta medullary nephrons are placed close to the junction of cortex and medulla.

Answer

To determine which statement is not true about nephrons, let's analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding Nephrons**: Nephrons are the functional units of the kidneys, responsible for filtering blood and forming urine. There are two main types of nephrons: cortical nephrons and juxtamedullary nephrons.

2. **Analyzing the Statements**:
- **Option A**: "Cortical nephrons are more common."
- This statement is true. Approximately 85% of nephrons are cortical nephrons, which are primarily located in the outer cortex of the kidney.

- **Option B**: "Cortical nephrons have short loops of Henle."
- This statement is also true. Cortical nephrons have shorter loops of Henle that do not extend deep into the medulla.

- **Option C**: "In juxtamedullary nephrons, the blood first passes through the capillaries of glomerulus."
- This statement is true as well. In juxtamedullary nephrons, blood is filtered through the glomerulus before entering the peritubular capillaries.

- **Option D**: "The glomeruli of juxtamedullary nephrons are placed close to the junction of cortex and medulla."
- This statement is **not true**. The glomeruli of juxtamedullary nephrons are actually located deeper in the cortex, near the boundary with the medulla, but not necessarily "close" to the junction. They are positioned more towards the medulla compared to cortical nephrons.

3. **Conclusion**: Based on the analysis, the statement that is not true about nephrons is **Option D**.

### Final Answer:
The statement that is not true about nephrons is: **"The glomeruli of juxtamedullary nephrons are placed close to the junction of cortex and medulla."**

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