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
Delayed prolonged leakage following tissue injury is due to: 
Select and explain. 
A. Cytokine mediated vasodilation, B. Histamine, C. Endothelial retraction, D. Direct effect of the injuring agent
D: Direct effect of the injuring agent
Answer: D: Direct effect of the injuring agent 
Explanation: Delayed prolonged leakage is believed to be caused either by the direct effect of injurious agent or by cytokine mediated endothelial retraction. It is not caused by cytokine mediated vasodilatation and cytokine mediated endothelial retraction is not provided in the options. Direct effect of injuring agent is therefore the single best answer of choice. Ref: Robbin's Illustrated Pathology, 7th Edition, Pages 51, 52 ; Pathology By Holliman, 4th Edition, Page 22