The angioarchitecture of the rat mandibular joint bilaminar zone.

In mammals, temporomandibular-joint articular disc attachments have a bilaminar pattern. The three-dimensional angioarchitecture of the bilaminar zone in the adult rat was described using scanning election microscopy of microvascular corrosion casts (47 specimens) and light microscopy of Indian ink-injected, cleared, thick-sectioned temporomandibular joints (6 specimens). The bilaminar zone had an axial core of feeder vessels composed primarily of flat venules which were organized in plexuses. Arterioles were few and slender. In both laminae, there were usually three branching levels until vessels approached the surface of the lamina, where a dense capillary meshwork was formed. Both laminae ended abruptly at the periphery of the avascular disc with a single, slightly undulating marginal vessel. This marginal vessel, which faced the avascular disc, was definitely larger in diameter than the other superficial capillaries and was rather a postcapillary venule than a capillary. Functionally, this marginal venule might be important in sustaining nutrition of the avascular disc centre by allowing bidirectional blood flow during jaw movements.