MH 065-066 Aorta and Vena Cava

Elastic Artery & Large Vein
(H&E)

Compare the features of the artery with its companion vein.

• Aorta - an elastic artery. The tunica media is the thickest layer and contains prominent elastic tissue.
  • Tunica Intima - inner layer composed of the endothelium, subendothelial connective tissue and a thin layer of elastic fibrils (the internal elastic membrane).
  • Tunica Media - middle layer composed of alternating layers of circumferentially arranged smooth muscle and wavy sheets of elastic fibers.
  • Tunica Adventitia - outer layer of dense irregular connective tissue.
    • Vasa Vasorum - blood vessels that supply the tunica adventitia and tunica media.
    • Nerves - regulate the contraction of the smooth muscle.
• Vena Cava - a large vein. The wall is thinner and has less distinct layers than the aorta.
  • Tunica Intima - inner layer composed of endothelium and a thin layer of connective tissue.
  • Tunica Media - middle layer consists of only a few (3 to 8) layers of smooth muscle.
  • Tunica Adventitia - outer layer of dense irregular connective tissue containing longitudinal or spiral arrangements of collagen fibers and smooth muscle.
    • Vasa Vasorum - blood vessels that supply the tunica adventitia and tunica media.
    • Nerves - regulate the contraction of the smooth muscle.
    • Adipose Cells - common in the adventitia of veins.

Elastic Artery & Large Vein
(Verhoeff Stain)

These are the same specimens except they were stained with Verhoeff. Although unstained with H&E, elastic tissue stains black with Verhoeff.

Compare the features of the artery with its companion vein.

• Aorta - an elastic artery. Prominent elastic tissue occurs in a thick tunica media.
  • Tunica Intima - inner layer with scattered elastic fibrils (black) in the subendothelial connective tissue.
  • Tunica Media - middle layer composed of alternating layers of circumferentially arranged smooth muscle (unstained) and wavy sheets of elastic fibers (black).
  • Tunica Adventitia - outer layer with none or scattered elastic fibrils (black).
• Vena Cava - a large vein. Very little elastic tissue occurs in the wall of veins.