Ultrastructure of normal rat synovial membrane.

Electron microscopic study of synovial membranes of many animal species has added materially to our understanding of the structure and function of this organ. The fine structure of the synovium of man (Barland, Novikoff, and Hamerman, 1962; Roy, Ghadially, and Crane, 1966), guinea-pig (Wyllie, More, and Haust, 1964), rabbit (Ghadially and Roy, 1966), calf and dog (Langer and Huth, 1960), and cat (Lever and Ford, 1958) have been well documented, but rat synovium has not been studied in this fashion. During the course of our investigations of normal and pathological synovia we had occasion to examine the synovium of this animal and found that it shows some features quite unlike any that have been observed in other species. It is therefore worthwhile to report these findings.