A small Introduction on different vascular layers:The walls of all blood vessels, except the very smallest, have three distinct layers, or tunics( 'covering') , that surround a central blood-containing space, the vessel lumen. The innermost tunic is the tunica intima which is in direct contact with the blood in the lumen. This tunic contains the endothelium. The middle tuinic, the tunica media is mostly contained of smooth muscle cells, elastin and collagen fibers. The outermost layer of a blood vessel wall, the tunica externa(adventitia) is composed of loosely woven collagen fibers that protect and reinforce the vessel and anchor it to surrounding structure.
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As for the biomechanical properties of the vascular tissue, there has been quite a large number of studies done. Some of these studies report inflation-extension types of experiments done on scaffold of adventitia removed from a whole vessel. Others, have just removed out the adventitia and focused on media. The question is :
Is it really possible for all type of vessels to take out adventitia out of the vessel mechanically?
To my knowledge, this seems quite a local and specie dependent property. It looks that in some arteries , such as human femoral arteries, you can easily separate the adventitia from the rest of the vessel. However, according my experiments, it is almost impossible to take it as a whole intact cylinder out from common carotid, femoral, abdominal arteries and Jagular,facial,femoral,abdominal veins of rabbits. As for common carotid of rats, I may say, it may be possible though I had never really done it.
let's consider that you have done it. Since it is a kind of bulky collagen fibers, it does not seem really impermeable to liquids. Thus, inflating of this layer, even if we can get it from the artery, seems quite a hard job.
Have you ever tried working with adventitia layer separately in inflation-extension tests? I would appreciate as you inform me on the subject.
picture taken from : reference
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