Ultrastructural changes associated with weaning in the mandibular condyle of the rat
Copray, J.C.; Liem, R.S.
Acta Anatomica 134(1): 35-47
1989
ISSN/ISBN: 0001-5180 PMID: 2718714 Document Number: 328036
To determine the postnatal structural changes due to increasing articular activity, we have compared the development posteriorly and posterosuperior superficial layers of the rat mandibular condylar cartilage by electron microscopy. In contrast to the uniform development posteriorly, the posteriorly, the posterosuper articular zone showed an extensive remodelling process with collagen breakdown and replacement between the ages of 21 and 28 days, i.e. during weaning. Enlarged spheroid fibroblasts contained numerous micropynocytotic vesicles, collagen debris enclosing vacuoles and a nuclear fibrous lamina enveloping the nucleus; abundant electron-dense amorphous material was present in the matrix as well as covering the surface. An increased number of metabolically active fibroblasts was supplied by the mesenchymal stem cells of the underlying chondrogenic zone. The adaptation process resulted in the replacement of small randomly oriented collagen fibers by large compact bundles running parallel to the glenoid fossa, providing protection to the condyle against excessive were and tear during incisal biting and grinding. The direct local relationship between (ultra) structure and functional load can be utilized in experimental research on the role of biomechanical forces in mandibular condylar growth and development.