Crimping of collagen in the intra-articular disc of the temporomandibular joint: a comparative study

Very occasional reference is made to the presence of collagen crimps in the fibre bundles of the intra-articular disc (LAD) of the temporomandibular joint (TMJ). As the crimp structure may confer important biomechanical properties on the LAD, the present study was undertaken to determine its distribution in a variety of mammals, including humans. LADs from the rat, rabbit, guinea pig, ferret, sheep, marmoset and human were either sectioned or examined as whole mount preparations with polarized light. Apart from the guinea pig, where fibre bundles in the central region of the disc showed considerable overlap and masking of the crimp structure, the anteroposterior aligned fibres in the central region of all remaining animals showed the conspicuous presence of crimps. The periodicity of the crimp distance varied between about 10 and 30 mu m. There was variation of the crimp periodicity between animals and between regions of the same disc. The crimping was associated with undulations along the length of the collagen fibres visible at the light microscope level using routine staining. The possible significance of crimping in association with internal derangement is discussed.