Fig. 6. (A-C) Immunolocalisation of osteopontin in bones. Light microscopic localisation by silver enhancement. (A) Osteopontin localisation in long bone of a control mouse. Note labelling in the bone matrix and the cement lines. Adjacent to the ruffled border of the osteoclast (OC) a low level of label is apparent. (B,C) Localisation of osteopontin in long bone of a doubly deficient mouse. A high level of labelling (arrows) is seen adjacent to the ruffled border of the osteoclast. (D-G) Electron microscopic localisation of osteopontin in bones. (D) Ruffled border area (RB) of an osteoclast of a control mouse. Gold particles (arrowheads) indicate the presence of osteopontin in the bone matrix at some distance from the ruffled border. (E) Ruffled border area of an osteoclast of a LAP-deficient mouse. Note the presence of a small number of gold particles (arrowheads) adjacent to the ruffled border membrane (B, bone). (F) Ruffled border area of an osteoclast of a LAP/Acp5 doubly deficient mouse. A large number of gold particles (arrowheads) are seen adjacent to the ruffled border membrane. (G) Intracellular vacuole (arrow) in an osteoclast of a doubly deficient mouse. The presence of osteopontin in the vacuole is indicated by a high number of gold particles (arrowheads). Scale bars: 20 µm in A-C; 0.18 µm in D; 0.25 µm in E,F; 0.15 µm in G.