A MICROSCOPIC AND IMMUNOCYTOCHEMICAL STUDY OF STRUCTURAL-CHANGES IN DYSFUNCTIONAL HUMAN TEMPOROMANDIBULAR-JOINT DISCS

The central part of 12 articular discs from patients with serious alte rations in function of the temporomandibular joint were investigated. The control discs were removed at autopsy from individuals who did not have any such functional defects. The anomalous discs had an increase d cellular component; fibrocytes, fibroblasts, numerous myofibroblasts and, less frequently, smooth muscle cells and mast cells were present . The myofibroblasts, which had numerous bundles of thin filaments in the cytoplasm, were positive to the immunocytochemical reaction with a ntibody to a-smooth muscle actin. In one disc only a large part had ch anged into a mostly fatty tissue. In the majority of the altered discs , the part examined, which usually is neither vascularized nor innerva ted, was characterized by the presence of numerous blood vessels. Besi des the capillary network several larger vessels were present. In one disc, several myelinated and unmyelinated fibres, isolated or in nerve bundles, were also seen. These observations show that the disc fibrou s tissue may undergo deep structural modifications that appear to indi cate not only a capacity for repair but also an ability to adapt to ne w functional conditions.