This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Leukocyte migration through endothelium is induced by ? 
Select and explain. 
A. Selectin, B. N CAM, C. C CAM, D. PECAM
D: PECAM
Answer: D: PECAM 
Explanation: Ans. is 'd' i.e., PECAMMigration of the leukocytes through the endothelium is called transmigration or diapedesis.Transmigration of leukocytes occurs mainly in postcapillaryvenules.The molecules involved in transmigration are member of the immunoglobulin superfamily called CD31 or PECAM-1 (platelet endothelial cell adhesion molecule).