<prompt> Angiofibroma bleeds excessively because -It lacks a capsuleVessels lack a contractile componentIt has multiple sites of originAll of the above  <response>: 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 epistaxisBleeding cannot be controlled by application of adrenaline, a potent vasoconstrictor. 