FURTHER ULTRASTRUCTURAL STUDIES ON TEMPOROMANDIBULAR JOINT OF GUINEA PIG

A light and electron microscope study of the temporomandibular joint indicated the following. The articular disc can be readily divided into three zones: the superior, and the inferior articular zones, and the central zone. The central zone contains small islands of cartilage surrounded by crisscrossing bundles of collagen fibers. The supraosseous tissue lining the articular fossa consists of three zones: a superficial zone, zone I, a dense fibrous zone, zone II, and a highly cellular zone which abuts on the underlining osseous tissue and appears to be concerned with bone formation. The articular surfaces of the disc and the fossa are limited by a thin layer of dense amorphous material subjacent to which is an open network of small collagen fibrils about 200 Å in diameter. The matrix in the deeper part of the fossa and the disc contain interwoven bundles of tightly packed collagen fibers, the diameter of the fibrils ranging from 200 to 1800 . The significance of these findings is discussed. © 1969 Academic Press, Inc.