Comparison of age-associated degeneration of articular cartilage in Wistar and Fischer 344 rats.

We have carried out a comparison of cartilage degeneration that develops spontaneously with age in the Wistar and Fischer 344 rats. Young adult (6-month-old) Wistar rats were essentially free of any relevant lesion in the articular cartilage of the knee. Aged (24-month-old) Wistar rats had minimal to mild lesions found mainly in the medial tibial plateau. These lesions were indicated by a focal loss of toluidine blue staining and limited fibrillation. Approximately 68% of the old Wistar rats had some degree of pathologic change. In comparison, 100% of the Fischer 344 rats examined, both young and old, had cartilage degeneration. However, the severity of the lesions increased with age. These two rat strains have variable degrees of spontaneous age-associated cartilage degeneration and would be suitable for testing treatments to prevent or repair the cartilage damage.