Abstract
To investigate three-dimentional ultrastructures of the muscle and tendon junction, the rectus femoris muscle, vastus lateralis and gastrocnemius muscle, rabbits's muscles were observed by scanning electronic microscopy (SEM) . The changes in this junction were observed during muscle contraction and relaxation. The observation by an optical microscopy were also made to obtain additional information. 1. The muscle tissue could be relatively clearly distinguished from the tendon tissue. They did not overlap each other. 2. The tendon appeared to form a plate-like shape at the junctional area and a unilateral site (boundary surface) of the tendon connected with the tip of the muscle. At the binding site, the tip of the muscle fiber and myofibril connected aslant with the boundary surface of the tendon. 3. The binding status between the muscle and the tendon was observed only at the sagittal surface and a frontal surface of the muscle. A transverse section of the binding site was unable to observe. 4. The connective tissues of the muscle such as endomysium and perimysium were transferred to collagen fibers of the boundary surface, and the muscle and the tendon were cennected through collagen fibers. 5. The tip of the muscle fiber runnel aslant to the boundary surface of the tendon, where each myofibril connected with the boundary surface of the tendon by a fine collagen fiber. Myofibrils were bound to each other with T-system. 6. The terminal end of the myofibril was Z-membrane. A fine collagen fiber connected with the terminal sarcomere, and thereby connected the boundary surface of the tendon with myofibril. 7. On the observation of the sagittal surface of the muscle, an angle of the incidence of the muscle to the tendon increased during muscle contraction and decreased during relaxation.
