Biomechanical and ultrastructural studies on the elastic wing tendon from the domestic fowl.

The interaction between collagen and elastin networks under conditions of load-extension has been studied in the elastic wing tendon of the domestic fowl. The load-extention curves obtained could be divided into two regions, the first region representing the ability of the tendon to undergo great extension at low tension, the second representing a limit region where the collagen of the tendon appears to become fully extended. Following removal of the elastin network with pure elastase only the second region of the curve persisted, indicating that elastin is largely responsible for the mechanical event represented by the first region of the curve. The collagen network of tendons apparently is normally held in a folded conformational state by elastin, for elastase treatment results in elongation of tendons even in the absence of loading. Complete removal of elastin, and alignment of collagen bundles were confirmed ultrastructurally in the elongated tendons. The breading load of the elastase-treated tendons was also significangly reduced, indicating that an elastase-sensitive component is a limiting factor in determining the ultimate strength of the tendon.