A–C: In osteoclasts on bone, F-actin (A) and V-ATPase (B) co-localize (C) in a patchy distribution within the F-actin rings. D–L: Like osteoclasts on bone, osteoclasts incubated on vitronectin show prominent F-actin staining in the actin ring/crescent, and noticeable F-actin staining within the ring/crescent. The F-actin within the actin ring tended to represent a greater proportion of smaller (D) than larger diameter (G, J) actin rings. V-ATPase (E, H, K) colocalizes with F-actin (F, I, L,). In all cells the F-actin/V-ATPase is present peripherally and as more central patches. C, F, I, L are counterstained with DAPI. Bar 10 µm (A–C), 5 µm (D–F, J–L) and 25 µm (G–I).