Ultrastructural evidence of vascularization of the central zone of the temporomandibular joint disc in human fetus

The present study examined the ultrastructural features of the articular discs of the temporomandibular joint (TMJ) of nine human fetuses aging from 21 to 28 weeks. The specimen of the fetal articular discs was sectioned frontally and sagitally and examined under the scanning electron-microscope. The ultrastructural survey of the architecture of the articular disc revealed three bands composed of fibrocartilaginous tissues in the articular disc: namely, 1) anteromedial longitudinal fibers, the dominant component in the superior and inferior portions; 2) anteroposterior transversal fibers, 3) central diagonal fibers. The central portion of the articular disc showed scattered blood vessels containing erythrocytes. To our knowledge, this is the first description of the presence of blood vessels in the central articular of the human TMJ articular disc. This evidence is also lacking in classic textbooks of Anatomy and Developmental Biology.