elastic arteries (histology)

Last reviewed 01/2018

Elastic arteries are those adapted to receive blood at moderate to high pressure near to the outflow tracts of the heart. Examples include the aorta, pulmonary trunk and the main branches of the arch of the aorta. The structure of their walls is on a continuum with the muscular arteries distally. They are adapted for conduction of blood and the transmittance of the energy of the pressure wave.

Their walls consist of:

• tunica intima:
• endothelium and basal lamina:
• simple squamous epithelial cells joined by tight junctions
• pinocytotic transport across membrane
• subendothelial connective tissue containing:
• elastin and collagen fibres
• smooth muscle cells and occasional fibroblasts
• internal elastic lamina: longitudinally oriented elastin fibres

þþ thickest layer

• at least 50 sheets of interconnected elastin fibres arranged in a concentric, coiled manner
• between each sheet is a layer of smooth muscle cells:
• spiral around wall of vessel, each cell connected to other smooth muscle cells via gap junctions
• secrete elastin and collagen fibres (types I,III and IV)
• tunica adventitia:
• thinnest of the layers
• greater proportion of collagen fibres in deference to elastin fibres; probably an adaptation to prevent over-distention of the vessels wall
• cellular elements include macrophages and fibroblasts
• vasa vasorum pass along this layer:
• vascular supply to the outer layers of the artery
• send perforating branches in to the tunica media and the subendothelial layer