Comparison and changes in the articular, mandibular condylar and growth-plate cartilages during the onset and healing of rickets in rats

Abstract

A comparison of the changes in the articular, mandibular condylar and growth-plate cartilages was made in rachitic rats. In the rachitic rat articular and condylar cartilages, the changes were similar. Both showed an increase in the width of cartilage, but only in the zone of hypertrophic cartilage. The rachitic tibial growth plate demonstrated the changes previously described by other authors, including resumed cartilage removal. Resumed cartilage removal was never seen in the articular or condylar cartilages. After vitamin D administration, the hypertrophic type of cartilage in the tibial articular cartilage was rapidly reduced in width and transformed into the non-hypertrophic form. The rachitic cartilage in the condyle was rapidly narrowed and was usually restored to normal by the tenth day, the development of calcification being similar to that seen in the early post-embryonic period of the condyle. During healing, the calcification of the growth plate resembled for a short time the pattern seen in the tibial anlage, and the condylar and articular cartilages. The rachitic disorder brings about a retrograde effect on the cellular characteristics of the tibial growth plate, while making more prominent the inherent embryonic nature of the articular and condylar cartilages.