An ultrastructural study of age-associated changes in the rabbit synovial membrane.

The synovial membranes of 5 young rabbits about 6 weeks old and 5 older rabbits about 3-4 years old were studied with the light and electron microscopes, with a view to discovering any age-associated changes that might occur. Several age-associated changes were noted. These included: (1) a reduction in the overall population of synovial intimal cells; (2) a statistically significant reduction in type B cells and a relative increase in type A cells; (3) the emergence of atrophic cells poorly endowed with organelles; (4) decreased vascularity; and (5) fibrosis.