The three-dimensional configuration of the elastic fiber network in canine saphenous vein. A stereo scanning electron microscopic study.

Stereo scanning electron microscopy was used to study the normal arrangement of elastic fibers in canine saphenous veins. Selective alkali digestion and autoclaving exposed a network of interconnecting elastic fibers throughout the venous wall. 14 normal saphenous veins were surgically removed from 7 healthy dogs. Unfixed 1-cm segments of the isolated specimens were digested by sonication for 30 min in 0.5 N NaOH solution and then autoclaved for 30 min. The digested specimens were then fixed and routinely prepared for scanning electron microscopy. Large longitudinally oriented fibers in each tunica branched and anastomosed with adjacent fibers. Small fibers branched off at almost right angles and interconnected the longitudinal fibers. The configuration of the elastic network varied between the tunicae of the venous wall. The different networks were interconnected by anastomosing fibers of adjacent tunica to form a single elastic cylinder throughout the venous wall. The internal elastic lamina consisted of a single layer of fibers with a fishnet-like arrangement around the periphery of the luminal surface. Large, longitudinally oriented elastic fibers of the tunica media branched and anastomosed as in the internal elastic lamina. However, they also had tangential orientation and traversed different levels within the media. As a result, stratified layers were not formed. The external lamina consisted of several parallel layers of longitudinally oriented ribbons of elastic. Thick fibers interconnected these broad ribbons on the same and adjacent levels to form discontinuous layers. The configuration of the elastic network of the canine saphenous vein is compared to that previously reported for human saphenous vein. It is suggested that the architecture of this elastic network would contribute to vascular integrity and flexibility as well as aid in the distribution of stress throughout the venous wall. Basic knowledge of the elastic fiber network in this vein may be applied to future studies of diseased and grafted vessels.