Choose where there are vessels of vessels? a. arteries b. veins c. lymphatic vessels d. in veins and lymphatic vessels e. in all vessel correct option
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Answer: e. In all vessels
The question asks about vasa vasorum - Latin for "vessels of vessels" - the small blood vessels that supply the walls of larger blood vessels themselves.
What are Vasa Vasorum?
Vasa vasorum are networks of small arterioles, capillaries, and venules found in the tunica adventitia (and outer tunica media) of large blood vessels. Their function is to deliver oxygen and nutrients to the cells of the vessel wall that cannot be nourished by simple diffusion from the lumen alone.
"Just as the heart wall has its own coronary vasculature to supply nutrients and O2 locally, large vessels usually have vasa vasorum ('vessels of the vessel'): arterioles, capillaries, and venules in the adventitia and outer part of the media."
- Junqueira's Basic Histology, 17e
Which vessels have Vasa Vasorum?
Vasa vasorum are found in:
| Vessel Type | Vasa Vasorum? |
|---|---|
| Large elastic arteries (e.g., aorta) | Yes - in adventitia |
| Muscular arteries | Yes - may be present |
| Large veins | Yes - more abundant than in arteries (because they carry deoxygenated blood, so diffusion from the lumen is less efficient) |
| Large lymphatic vessels | Yes - the walls of large lymphatics are also supplied by vasa vasorum |
| Small arteries/arterioles/capillaries | No - their walls are thin enough to be nourished by direct diffusion |
Key point from Junqueira: "Because they carry deoxygenated blood, large veins commonly have more vasa vasorum than arteries."
The Histology Image
Below is a textbook photomicrograph (H&E, x100) of a large muscular artery showing vasa vasorum in the adventitia:
Labels: SM = smooth muscle (media), E = elastic fibers, A = arterioles of vasa vasorum, V = venule of vasa vasorum, N = nerve (nervi vasorum). The vasa vasorum (A, V) are visible in the adventitia at the bottom.
Why not just arteries or veins?
- Option a (arteries only) - incorrect: veins and lymphatics also have them
- Option b (veins only) - incorrect
- Option c (lymphatics only) - incorrect
- Option d (veins + lymphatics) - incomplete, misses arteries
- Option e (all vessels) - correct - large arteries, large veins, and large lymphatic vessels all possess vasa vasorum
The answer is e - vasa vasorum are present in all large vessel types (arteries, veins, and lymphatics).
Source: Junqueira's Basic Histology, 17e; Histology: A Text and Atlas (Eroschenko)
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