Scanning and transmission electron microscopic studies on the fiber architecture of the articular disc of rat temporomandibular joint in reference to its functional significance (author's transl)

Abstract

To define the functional significance of the disc of the temporomandibular joint, 80 rats aged 2, 5, 12, 20, 30, 40, 60 days were used in this study. After weaning they were separately fed on solid and powder diet. After perfusion, the condyle with the articular disc was removed. The specimens were treated by the orthodox procedures for electron microscopy. Fiber architecture of the developing discs was examined electron microscopically.1. Scanning electron microscopically, the primordial ridge, which is the foundation of the typical ridge on the upper surface of the adult disc, appeared 12 days after birth in the sucking rats, and its formation was completed 40 to 60 days after birth in the rats fed on solid diet.2. Transmission electron microscopically, in the fiber arrangement the disc was observed to be a tendon-like tissue in the 40 to 60-day-old rats fed on solid diet.3. In the 40 to 60-day-old rats fed on powder diet, the disc was still in the suckling stage.4. The developing disc changed its surface structure adapting itself to the properties of the different kinds of diet after birth, and also its arrangement of the collagen fibers responding to the mechanical stress applied to the joint during mastication.