Distribution of elastic fibres in the developing rabbit craniomandibular joint.

The biomechanical properties of the CMJ disc depend upon the composition and organization of the extracellular matrix. Elastic fibres are important elements of the matrix and may be in part responsible for the resilience of the disc during jaw movements. Elastic fibres first appeared after the establishment of a miniature CMJ at 23 days of prenatal development. The first elastic fibres appeared in the antero-inferior and postero-inferior attachment regions of the disc. In the newborn rabbit there were elastic fibres in the articulating surfaces of the joint and by one week fibres could be seen in the intermediate zone portion of the disc. At two weeks, when the animals were beginning to experiment with solid food, the disc band areas showed accumulations of elastic fibres and proteoglycans. The findings suggest that the elastic elements of the disc, squamosal and condylar articulations may have a resilience function which develops in response to functional loads placed upon the joint as the rabbit grows and changes diet.