Structure and proteoglycan composition of specialized regions of the elastic tendon of the chicken wing

Abstract

The elastic tendon of the avian wing has been described by others as a unique structure with elastic properties due to the predominance of elastic fibers in the midsubstance. Further analyses of the tendon have shown it to possess five anatomically distinct regions. Besides the major elastic region, a distally located fibrocartilage and three tendinous regions are present. The tendinous regions connect: (1) the muscle to the elastic region, (2) the elastic region to the fibrocartilage and (3) the latter to the insertion site. The elastic region possesses thick and abundant elastic fibers and very thin, interconnecting collagen fibers. The collagen fibers in the sesamoid fibrocartilage are thick and interwoven, defining spaces occupied by fibrochondrocytes embedded in a non-fibrillar and highly metachromatic matrix. Biochemical analyses have shown that the fibrocartilage has about tenfold the amount of glycosaminoglycans (GAGs) found in the other regions. The main GAG in this region was chondroitin sulfate (CS) (plus keratan sulfate as detected immunocytochemically), while the other regions showed variable amounts of CS, dermatan sulfate (DS) and heparan sulfate. Further analyses have shown that a large CS-bearing proteoglycan is found in the fibrocartilage. The elastic region possesses two main proteoglycans, a large CS-bearing proteoglycan (which reacted with an antibody against keratan sulfate after chondroitinase ABC treatment) and a predominant DS-bearing proteoglycan, which showed immunoreactivity when assayed with an anti-biglycan antibody. The results demonstrate that the elastic tendon is a complex structure with complex regional structural and compositional adaptations, suited to different biomechanical roles.

Cell encapsulation using biopolymer gels for regenerative medicine

“…Tendons and fibroblasts are rich in fibroblasts which secrete ECM containing collagen type I/III, elastin and proteoglycans (Carvalho et al 2000;Chan and Leong 2008;Cheema et al 2007;Cleary et al 1967). Collagen and fibrin gel encapsulation of fibroblasts have been shown to have promise for tissue engineering of tendons and ligaments.…”

Collagen fibrillogenesis in tendon development: Current models and regulation of fibril assembly

“…Tendons are dense fibrous connective tissues that connect muscle to bone (Birk and Trelstad, 1986;Carvalho et al, 2000). Composed of closely packed parallel collagen fiber bundles, these tissues are high in tensile strength and function to transmit forces and stabilize joint structures (Birk and Trelstad, 1986;Eriksen et al, 2002;Edom-Vovard and Duprez, 2004).…”

Matrix metallopeptidase 2 activity in tendon regions: effects of mechanical loading exercise associated to anabolic-androgenic steroids

“…Tendons are specialized structures, which are responsible for transmitting muscle forces to bone (Carvalho et al 2000;Ker 2002;Koob and Summers 2002;Maganaris and Paul 2002;Ritty and Herzog 2003). Fibroblasts monitor the magnitude and direction of force (Koob and Summers 2002), synthesizing and maintaining most extracellular matrix (ECM) elements, including collagen, proteoglycans (PGs) and other components (Magnusson et al 2003).…”