Ansa nephroni is lined by ?
**Core Concept**
Ansa nephroni, also known as the ansa nephroni or the nephron's vascular bundle, is a collection of small blood vessels surrounding the nephron in the renal cortex. It plays a crucial role in the regulation of blood flow to the nephron and is involved in the pathophysiology of various kidney diseases.
**Why the Correct Answer is Right**
The ansa nephroni is lined by a single layer of flat, endothelial cells. This unique lining allows for the regulation of blood flow to the nephron and helps to maintain the delicate balance of electrolytes and water in the body. The endothelial cells in the ansa nephroni also produce various vasoactive substances that help to modulate blood pressure and renal function.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the ansa nephroni is not lined by smooth muscle cells, which are involved in the regulation of blood pressure but not in the lining of this vascular structure.
* **Option B:** This option is incorrect because the ansa nephroni is not lined by pericytes, which are a type of glial cell that surrounds blood vessels in the brain but not in the kidney.
* **Option C:** This option is incorrect because the ansa nephroni is not lined by mesangial cells, which are involved in the regulation of blood flow in the glomerulus but not in the lining of this vascular structure.
**Clinical Pearl / High-Yield Fact**
It is essential to remember that the ansa nephroni plays a critical role in the regulation of blood flow to the nephron, and damage to this vascular bundle can lead to various kidney diseases, including hypertension and renal failure.
**Correct Answer: D. Endothelial cells**