[Formation of collagen fibrils in the synovial membrane in rheumatoid arthritis (electron microscope study)]

As demonstrates investigation of the synovial membrane biopsies obtained in patients suffering from rheumatoid arthritis, excessive formation of collagenous fibrillae results from participation, in this process, of activated synoviocytes B, pericytes and fibroblasts capable to intensify secretion and synthesis of tropocollagen. Aggregation of tropocollagen molecules into the collagenous fibrillae occurs in the areas where the inflammation acquires a chronic form where the cellular detritus is accumulated and where immune complexes are deposited. In the places mentioned, together with assembling normal collagenous fibrillae certain pathological fibrillar forms are observed, such as: fibrillae with an increased diameter, fibrillae with a changeable optic density of transversal streakness, those deprived of it, as well as segmentary scrap of fibrillo-formation. It is suggested that disturbance of the tetrary polymerization of the collagenous structures, that occurs at rheumatoid arthritis, prevents the functional-loading rearrangement and reabsorption of excessive fibrillae. Together with phenomena of tropocollagen hypersecretion from activated mesenchymal cells, this results in collagenous hyperfibrillogenesis, in fibrosis of the joints and in their irreversible rigidity.