During leukocyte extravasation, movement of the neutrophil through the endothelial intercellular junctions (diapedesis) is mediated primarily by which molecule?
- A PECAM-1 (CD31) ✓
- B E-selectin
- C VCAM-1
- D GlyCam-1
Correct answer: A. PECAM-1 (CD31)
Explanation
After firm adhesion, the neutrophil squeezes between adjacent endothelial cells at their borders, a step driven by PECAM-1 (CD31), which is expressed on both leukocytes and endothelial junctions. E-selectin mediates rolling, VCAM-1 binds VLA-4 on mononuclear cells for firm adhesion, and GlyCAM-1 on high endothelial venules binds L-selectin for lymphocyte homing. None of these mediate the junctional passage itself.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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