This section will examine the normal histology of the human aorta using histology slides stained with hematoxylin & eosin (H&E, non-specific) and elastin/trichrome (special) stains. Please refer to the sections How Are the Specimens Obtained and Prepared? and Video Lessons on Histology to learn more about the stains and histology slide preparation.

The thoracic aorta includes the aortic root, the ascending aorta, the arch, and the descending aorta. The aorta’s elastic properties depend on its wall structure, composed of three distinct histologic layers: intima, media, and adventitia.

It is primarily made up of collagen-dispersed connective tissue, fibroblasts and a network of nerves relaying mostly adrenergic responses. These fibers protect the aorta from overstretching and comprise the aorta’s protective outer shell.

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).

In the Hg group, distortion of the aortic wall is shown in (e) (dashed arrow) and change in tissue structure of the area is visible in (f), with rounded nuclei in the tunica intima (arrow), as...

We obtained surgical samples from ascending aortic aneurysms (n = 11), aortic root aneurysms (n = 3), and non-aneurysmal patients (n = 7), Aortic collagen and elastin content were examined via histological analysis, and immunohistochemistry techniques used to determine collagen I, III, and IV subtypes.

This is a longitudinal section through the normal aorta with an elastic tissue stain at low power. The intima is at the top, while the thick aortic media demonstrates parallel dark elastic fibers, here highlighted by the elastic stain. The smooth muscle fibers are between the elastic fibers.

The aorta is an elastic artery which has a relatively thick tunica intima bounded by endothelium and the internal elastic membrane. The internal elastic membrane, however, is less obvious here than in the smaller muscular arteries .

In addition to locating blood vessels, also observe the numerous sectioned nerves and adipose tissue. Note the presence of brown fat cells with their multilocular appearance. The blood vessels of the aorta, the vasa vasorum, should be identified in the tunica adventitia.

The cells that make up the tissues of the aorta include: Endothelial Cells: Line the lumen of the aorta and form a barrier between the blood and the vessel wall. Smooth Muscle Cells (SMCs): Found in the tunica media, these cells provide structural support and elasticity.