During angiogenesis recruitment of pericytes and periendothelial cells is due to
**Core Concept**
Angiogenesis is the process of formation of new blood vessels from pre-existing ones. It involves the coordinated action of various cell types, including endothelial cells, pericytes, and periendothelial cells. The recruitment of pericytes and periendothelial cells is a crucial step in the maturation and stabilization of newly formed blood vessels.
**Why the Correct Answer is Right**
The recruitment of pericytes and periendothelial cells is mediated by the action of angiopoietins, specifically angiopoietin-1 (Ang-1) and its receptor Tie-2. Ang-1 binds to Tie-2 on the surface of endothelial cells, which in turn recruits pericytes and periendothelial cells through the expression of Ang-2. This process is essential for the stabilization of newly formed blood vessels and the prevention of vascular leakage. The interaction between Ang-1 and Tie-2 also promotes the differentiation of endothelial cells into mature, functional blood vessels.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not specify the mechanism of pericyte and periendothelial cell recruitment.
* **Option B:** This option is incorrect because it refers to the action of vascular endothelial growth factor (VEGF), which primarily promotes endothelial cell proliferation and migration, but not the recruitment of pericytes and periendothelial cells.
**Clinical Pearl / High-Yield Fact**
Recall that the interaction between Ang-1 and Tie-2 is essential for the stabilization of newly formed blood vessels and the prevention of vascular leakage. This process is critical in various physiological and pathological conditions, including wound healing, inflammation, and cancer.
**Correct Answer:** C.