Histological studies of the development of the temporomandibular joint in the rat.

要旨

The early development of the mandibular condyle, the temporal bone, and the articular disc in the temporomandibular joint was investigated histologically in the rat from prenatal day 14 through postnatal day 6. Serial sagittal sections of each of these areas were prepared, and aldehyde fuchsin (AF) staining was used for the most part to determine the elastic fiber content of the sections.Semilunar areas, densely stained with AF, were identified on the posterior aspect of the mandibular condyle anlage on prenatal day 16. This region increased with time and developed into elastic fiber bundles of the retrodiscal tissue on postnatal day (P) O. The superior articular cavity developed on prenatal day 20, and the inferior articular cavity appeared on PO. Thus, the articular disc was discernible on PO. The articular disc contained abundant elastic fibers throughout: in the anterior band, the intermediate zone, and the posterior band. The posterior band of the articular disc contained abundant elastic fibers in the inferior region of the sagittal section, and fewer elastic fibers in the superior region. In the retrodiscal tissue a bundle of elastic fibers extended from the inferior region of the disc to the posteroinferior region, where the bundle divided into two branches. One proceeded inferiorly into the perichondrium of the mandibular condyle, and the other coursed superiorly in the posterior region and entered the adventitia of an adjacent large vein.

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