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: ENT
Angiofibroma bleeds excessively because - 
Select and explain. 
A. It lacks a capsule, B. Vessels lack a contractile component, C. It has multiple sites of origin, D. All of the above
B: Vessels lack a contractile component
Answer: B: Vessels lack a contractile component 
Explanation: The characteristic of JNA is that the vessels are just endothelial - lined spaces with no muscle coat.
As the contractile component (muscle coat) of vessels is absent, vessels have no ability to contract, i.e. vasoconstriction does not occur, and this accounts for :-


Severe and recurrent epistaxis
Bleeding cannot be controlled by application of adrenaline, a potent vasoconstrictor.