Development and distribution of elastic fibers in the mandibular joint of the mouse. A comparison of fetal, suckling, juvenile and adult stages

Development and distribution of elastic fibers were studied in mandibular joints of white Swiss mice which ranged from 15 days insemination age to three months postnatal. Paraffin sections were stained with Weigert's resorcin‐fuchsin and Verhoeff's elastic tissue stain. Elastogenesis does not begin until the major elements of the mandibular joint are present. The first distinct elastic elements appear as granules at the nineteenth to twentieth day insemination age. Early sites of elastogenesis occur in the peripheral portions of the articular disk, at the transition and continuation of fibrous disk tissue with the periarticular tissues, and with the periosteum around the neck of the mandible. The concentration, length and caliber of fibers is increased markedly during the suckling stage, especially in the walls of the medial and lateral recesses of the synovial cavities, and in the posterior continuation of the disk to form a fibroelastic band of attachment to the squamosal bone. Prominent bands of long elastic fibers appear in the epimysium of the lateral pterygoid and masseter muscles in the young adult. The central portion of the disk and the articular surfaces of the mandibular condyle and fossa contain no elastic fibers, confirming the contention that these surfaces are not particularly stress‐bearing. Stretch and shearing stresses are created, however, which require extensive elastic fiber development in other joint tissues.