MH 024-025-026 Mesentery

Click the thumbnail to show mesentery stained with hematoxylin & eosin.

Muscular Artery & Medium Vein
(H&E)

Muscular (or distributing) arteries convey blood from elastic arteries to the systemic circulation.

Compare H&E staining to that with Verhoeff and Azan.

- the large muscular artery has a pathologic thickening of the tunica intima.
- - inner layer composed of the endothelium, subendothelial connective tissue, and a prominent internal elastic lamina (wavy band that is unstained or light pink).
- - middle layer composed mostly of circumferentially arranged smooth muscle.
- - outer layer composed of well-organized dense irregular connective tissue.
- the companion veins to arteries have a larger diameter and a thinner wall with less distinct layers.
- - inner layer composed of the endothelium, subendothelial connective tissue, and an internal elastic lamina.
- - middle layer of only a few layers of circumferentially arranged smooth muscle.
- - outer layer composed of dense irregular connective tissue connective tissue containing longitudinal or spiral arrangements of smooth muscle.

Note the presence of other smaller muscular arteries and veins in this specimen.

Click the thumbnail to show mesentery stained with Verhoeff stain.

Muscular (or distributing) arteries convey blood from elastic arteries to the systemic circulation.

Compare Verhoeff staining to that with H&E and Azan. The staining of elastic tissue by Verhoeff highlights the internal and external elastic lamina.

- the large muscular artery has a pathologic thickening of the tunica intima.
- - inner layer separated from the tunica media by a prominent, wavy internal elastic lamina.
- - middle layer with dispersed fragments of elastin and a prominent external elastic lamina.
- - outer layer with variable amounts of elastin depending on the size of the vessel. Large vessels have several layers while smaller vessels have none.
- the companion veins to arteries have a larger diameter and a thinner wall with less distinct layers.
- - inner layer separated from the tunic media by a thin internal elastic lamina in larger veins, but is absent in smaller veins.
- - middle layer with dispersed fragments of elastin in larger veins, but absent in smaller veins.
- - outer layer with dispersed fragments of elastin in larger veins, but absent in smaller veins.

Note the presence of other smaller muscular arteries and veins in this specimen.

Click the thumbnail to show mesentery stained with azan.

Muscular (or distributing) arteries convey blood from elastic arteries to the systemic circulation.

Compare Azan staining to that with H&E and Verhoeff. The staining of collagen by Azan highlights the tunica adventitia.

- the large muscular artery has a pathologic thickening of the tunica intima.
- - inner layer is lightly stained because of the small amounts of collagen. (The internal elastic membrane is stained light pink.)
- - middle layer has scattered staining of the collagen fibers that support the circumferentially arranged smooth muscle.
- - outer layer is stained dark blue because of the collagen in the dense irregular connective tissue.
- the companion veins to arteries have a larger diameter and a thinner wall with less distinct layers.
- - inner layer is unstained (or lightly stained) because of the small amounts of collagen.
- - middle layer is lightly stained because of the small amounts of collagen.
- - outer layer is stained dark blue because of the collagen in the dense irregular connective tissue.

Note the presence of other smaller muscular arteries and veins in this specimen.