A woman suffering from rheumatism died of cardiac decompensation, microscopic examination of the internal organs revealed: collagen fibers bundles impregnated with plasma proteins, homogeneous, eosinophilic, picrinophilic when stained with van Gizon, Schick- positive, pyroninophilic in the Brasche reaction and argyrophilic in the impregnation with silver salts. Please indicate which pathological process in the connective tissue is the most common?