Ultrastructural evaluation of microcirculatory vessels in rheumatoid synovial membrane.

Since morphological lesions in microcirculatory vessels are often difficult to be found in the light microscope, the electron microscope investigations were performed on the synovial membrane biopsy specimens from 70 patients with rheumatoid arthritis (RA). Most common lesions referred to venules, capillaries and arterioles were swelling and proliferation of endothelial cells, adherence of lymphocytes, monocytes and neutrofiles to the endothelium, their margination and diapedesis. Also destructive changes in the endothelial cells, basement membrane thickening due to their multiplication and microthrombi were observed. Platelet aggregates, fibrin, fragments of desintegrated cells and deposits of granulofibrillary substance corresponding to fibrinoid necrosis were frequently seen. In 7 patients, lesions of this kind were found only in electronograms. It can be assumed that the evaluation of ultrastructural changes in the microcirculatory vessels may be of great significance as a complementary diagnostic examination in future determination of RA progression and further prognostication.