[Histological classification of rheumatoid synovitis compared with cell-kinetics and morphology of experimental immune synovitis (author's transl)].

During the course of the experimental immune arthritis of the guinea pig four phases can be distinguished: I=fibrinopurulent, partly ulcerative synovitis, II=granulocytic activee granulomatous synovitis, III=lymphocytic activ granulomatous synovitis, IV=synovitic sequelae with subintimal fibrosis. On the basis of cell-kinetic studies with initial and systemic labelling with 3H-thymidine of the synovial membrane and of the bone marrow it could be demonstrated that in this model the infiltrating cells as well as the structural cells belong to the monocyte-macrophage system. The typical multilayer of the lining cells of this immune synovitis therefore seems to be mainly as a type A cell hyperplasia of bone marrow derived cells instead of a local proliferation of the lining cells. Clinical cases of various joint diseases are described including symptoms, X-ray findings and histopathological studies. Depending on the stage of the clinical course and the number, localization and activity of the macrophages within the synovial membrane the reaction pattern can be classified in a new way using the categories mentioned above in the experimental model. Thus the classical picture of rheumatoid arthritis corresponds to the synovitis of the subintimal type. The polyarthritic syndrome which mostly is pathogenetically unclear in contrast is designated as synovitis of the intimal type. The same holds true for the activated arthrosis.