Lesions of articular, sternal and growth plate cartilage in rats.

Degenerative osteoarthritis was observed in the femur and sternum in specific pathogen free Fisher 344 rats at 13 and 19 months of age. Histological changes consisted of degeneration of the matrix and erosion in the articular cartilage of the femur. In the sternal cartilage, degeneration and necrosis of the matrix, formation of cysts, and cleft-like fractures were observed. In addition, degeneration of the matrix, appearance of eosinophilic streaking, and necrosis and fissure between the growth plate and epiphyseal trabeculae were seen in the femur. The changes in the sternum were essentially the same as the femur.