Slide 10
The joint surface of the preceding slide (slide 9) at a higher magnification. This is a raw bone surface. Beneath it is extensive new bone formation. The thickened bone and polished surface result in a gross, ivory-like appearance or eburnation. A developing "cyst" is included, its lumen containing strands of degenerating connective tissue and fluid. The condensation of loose connective tissue cells in the wall of the cyst indicates expanding fluid pressure. The fully evolved, sometimes loculated and apparently coalescent cysts are demonstrated in the preceding photograph (slide 9). The development of the cysts is accompanied by new bone formation.

Slide 11
This is a sagittal celloidin section through a distal interphalangeal finger joint. There is irregular hypertrophy of the bone at the articular margins of the distal phalanx. The cartilage is well preserved. No evidence of active inflammation is apparent. Although cartilage loss and osteophytes are both signs of osteoarthritis, they are poorly correlated with one another. Cartilage loss is more correlated with pain. Many people with only osteophytes have no pain. Transforming growth factor-b (TGF-ß) is the main cytokine stimulating formation of osteophytes. Interleukin-1 (IL-1) is the main cytokine mediating loss of cartilage.