During angiogenesis recruitment of pericytes and periendothelial cells is due to ?
**Core Concept**
Angiogenesis is the process of new blood vessel formation, which is crucial for tissue repair, growth, and metastasis of cancer. The recruitment of pericytes and periendothelial cells is a critical step in stabilizing the newly formed blood vessels.
**Why the Correct Answer is Right**
The recruitment of pericytes and periendothelial cells is mediated by the endothelial cell-derived factors, such as VEGF (vascular endothelial growth factor) and Ang-1 (angiopoietin-1). These factors activate the Tie2 receptor on the surface of pericytes and periendothelial cells, leading to their adhesion to the endothelial cells and subsequent incorporation into the vessel wall. This process is essential for the maturation and stabilization of the new blood vessels.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because pericytes and periendothelial cells are not recruited by the same factors that initiate angiogenesis, such as VEGF. While VEGF is essential for the initiation of angiogenesis, it is the endothelial cell-derived factors, such as Ang-1, that recruit pericytes and periendothelial cells.
**Option B:** This option is incorrect because the recruitment of pericytes and periendothelial cells is not a passive process. It requires the activation of specific receptors, such as Tie2, on the surface of these cells.
**Option C:** This option is incorrect because the recruitment of pericytes and periendothelial cells is not a result of the action of a single growth factor. It is a complex process that involves the interaction of multiple endothelial cell-derived factors.
**Clinical Pearl / High-Yield Fact**
The recruitment of pericytes and periendothelial cells is a critical step in the stabilization of new blood vessels, and its dysregulation has been implicated in various pathological conditions, including cancer and cardiovascular disease.
**Correct Answer: C. Angiopoietin-1**