Structure of large arteries: orientation of elastin in rabbit aortic internal elastic lamina and in the elastic lamellae of aortic media.

This study was designed to further our understanding of the elastic ultrastructure of vessels. Scanning electron microscopy and transmission electron microscopy were used to study the histomorphologic properties of the elastic fibers of rabbit aorta after purification of the elastin by means of hot alkaline treatments. The elastic fibers of whole rabbit aorta samples were also studied using confocal microscopy. Morphological assessment revealed that the elastin fibers contained in the elastic lamellae of media are perpendicular to the blood flow, and that the elastic fibers of the internal elastic lamina are parallel to the luminal flow. In conclusion, the structure of the elastin making up the elastic lamellae of the media is oriented in such a way as to sustain the circumferential mechanical stress of pulsation. By contrast, the structure of the elastin fibers that make up the internal elastic lamina provides little mechanical support for the circumferential tension, but can support longitudinal loading and act as a fenestrated membrane.