Scanning Electron Microscopy of the Normal and Rheumatoid Synovial Membranes

Normal and rheumatoid synovial membranes obtained in surgical operations were fixed in 10% formalin, dehydrated in aceton, dried in air, coated with gold and examined under a JMS-2 type scanning electron microscope.1. In the normal synovial surface, individual lining cells were protruded fairly uniformly into the joint cavity. These protrusions were covered with small papillary cytoplasmic processes.2. In the rheumatoid synovial membrane which was characterized, already on the macroscopic level, by a conspicuous unevenness of the surface and by a formation of unusual villi, the lining cells were protruded into the cavity more irregularly and sporadically than in the normal case. Some cells swelled up roundly high into the synovial cavity. The lining cells may carry lower and less conspicuous cytoplasmic processes than the normal ones. Some areas of the synovial surface looked smooth and amorphous suggesting a possible deposition of the muddy debris of the rheumatoid synovia.3. The present study proves that scanning electron microscopy provides an excellent method for studying and recording the surface aspect and pathological changes of the synovial membrane.