Scanning Electron Microscopy of Elastic System Fibers in the Articular Disc of the Rat Mandibular Joint

Abstract

Summary: Elastic system fibers (ESFs), i.e., microfibrils (putative oxytalan fibers), elaunin and elastic (true elastin) fibers, in the rat mandibular joint were studied mainly using scanning electron microscopy (SEM) and light microscopy (LM) with the aid of image processing. The present quantitative analysis using LM showed that the articular disc and capsule, which are the sites that receive physical compressive force during mastication, contained more ESFs than the articular cartilage of the mandibular joint. In addition, oxytalan fibers were the principal ESFs in all the articular components (capsule, articular disc, supraosseous layer of articular surfaces and articular cartilage). Subsequently, ESFs in the articular disc, which contained more thick ESFs, were closely examined by SEM using both collagen-and elastin-digestion methods. SEM showed networks of microfibrils beneath the articular surfaces (superior and inferior layers) in the thin central portion of the articular disc; the principal microfibrils ran at nearly right angles to the collagen fibers. The microfibrils were cemented with amorphous elastin, thickened and shifted towards interconnecting oblique fibers and many main ESF trunks, which were oriented in the direction of the layered wavy collagen fibers and parallel to the direction of applied force, to sustain the mechanical force. From the superior and inferior layers, the main ESFs shisfted towards the middle portion of the disc, transitional zone (synovial osteochondral junction) and the other articular components, showing no specific directivity. Transmission mission electron microscopy revealed that the thick main ESFs in the elastic network were elaunin fibers. The present study indicated that ESFs unite, branch and therefore construct an extensive and complicated protective stretchable network, which is interposed with the less tensible collagen network in the mandibular articular disc.Elastin system fibers (ESFs), which are usually differentiated as microfibrils (oxytalan fibers), elaunin and elastic fibers based on their staining properties and the distribution of the microfibrils and amorphous cementing elastin, play a particularly important role in the elasticity of connective tissue (CottaPereira,

Synovial fibroblasts self‐direct multicellular lining architecture and synthetic function in three‐dimensional organ culture

“…Conceptually, we envision that the outer surface of the sphere models the interface between synovial connective tissue and synovial fluid in the joint. For our 3‐D ECM scaffold, we selected Matrigel, which is a solubilized basement membrane preparation whose composition of matrix components (laminin, type IV collagen, and heparan sulfate proteoglycans) is similar to that of the dense ECM in the synovial lining (5, 8, 10, 43–54). Histologic examination of cultured micromasses revealed that FLS spontaneously accumulated and compacted at the micromass surface, displaying a remarkable resemblance to the appearance of the synovial lining in vivo (Figures 1A and C).…”

Alteration of structural and mechanical properties of the temporomandibular joint disc following elastase digestion

“…While the mechanical contribution of collagen fibers has been extensively studied, there are only few studies on the occurrence and distribution of elastin fibers in the disc (Clément et al, 2006; Detamore et al, 2005; Gross, Bumann, & Hoffmeister, 1999; Iwai‐Liao, Ogita, Tsubai, & Higashi, 1994; Keith, 1979; O'Dell, Burlison, Starcher, & Pennington, 1996). Therefore, the aim of the present study is to provide a structural–functional characterization of elastin fibers in the TMJ disc, in light of their contribution in healthy and degenerated conditions.…”