DEGRADATION OF ARTICULAR-CARTILAGE DURING THE PROGRESSION OF ANTIGEN-INDUCED ARTHRITIS IN MICE - A SCANNING AND TRANSMISSION ELECTRON-MICROSCOPIC STUDY

Ultrastructural changes of knee articular cartilage in C57B1/6 mice we re studied in the course of antigen-induced arthritis by means of scan ning acid transmission electron microscopy. First damages of the carti lage surface were seen one hour after arthritis induction. The earlies t signs were the loss of the superficial electron-dense layer as well as a progressive loss of proteoglycans in the cartilaginous matrix on the surface. Breaks of collagen fibres were already detected at the fi rst day of arthritis. The chondrocytes of the superficial cartilage la yer showed an increase of the intracellular membraneous system in the early phase of arthritis. Thereafter chondrocytes on the surface becam e more and more necrotic. On the 7th day of arthritis acute alteration s of cartilage had developed completely. Many lacunae of chondrocytes were opened and the cartilage surface showed deep structural defects w ith adhering cells, probably lymphocytes and macrophages. In the follo wing time these destructive processes were demonstrated along with cel lular proliferation as a sign of repair attempts in hyaline cartilage.