Elastic Type Arteries
1. Elastic type arteries
1.1. By definition they have multiple layers of elastic laminae in their media
1.2.2. Innominate, subclavian, carotids
1.2.4. Pulmonary arteries
An elastic type artery is defined by the presence of multiple layers of lamellar units in the media of the vessel.
Low and medium magnification of an elastic type artery stained with Movat pentachrome stain. The intima is a distinct layer with a thin fibrous tissue band (yellow brown). The media is composed of a series of lamellar units. In humans the ascending and thoracic aorta have 50-60 lamellar units. These units decrease in number as the aorta courses through the thorax and abdomen. The infrarrenal aorta has 20-30 lamellar units.
The lower image shows a series of lamellar units. A lamellar unit is the tissue comprised between two undulating black elastic lamellae. These black elastic lamellae are clearly delineated. Between two elastic lamellae there are smooth muscle cells with red cytoplasma and dark blue/purple nuclei. In turn the space between the smooth muscle cells and the nearest eslatic lamella (above or below it) contains other components of the extracellular matrix. Namely fibrous tissue (collagen) staining in yellow, and small amounts of proteoglycan (mucopolysaccharide material) in green color. A higher magnification image of the lamellar units of the aorta is shown here.
The arrangement and composition of the elastic lamellar units of the media is altered in diverse pathologic states.