The ultrastructure of experimental arthrosis in dogs.

Experimental arthrosis was induced in previously healthy joints in a group of dogs by injection of fluid aspirated from another joint of the same animal previously damaged by trauma under sterile conditions. Using electron microscopy progressive degenerative changes were observed at the surface of the joint, in the extracellular matrix, in the chondrocytes and in the pericellular band. The changes increased following serial injections of the joint fluid. In another series, the joints were injected either with the centrifuged concentrate or the supernatant fluid and a comparison made of the contrasting effects upon the cellular and extracellular structures.