Fig. 2. Endocytic activities of osteoclasts shift towards the ruffled border during resorption. Rabbit osteoclasts cultured overnight on dentine were incubated with vehicle control (A,C) or 10 µM cytochalasin D for 10 minutes (B,D) before the addition of FITC-BSA for 5 minutes and then either fixed directly (A,B) or washed and chased in medium without inhibitor and FITC-BSA for 30 minutes (C,D). FITC-BSA accumulates in the pit immediately below the cell only upon treatment with cytochalasin D (B, arrowheads). After the chase, endocytosis is only observed in cells that had been exposed to cytochalasin D (fluorescent structures inside of the cell are indicated with arrows in D), whereas vehicle-treated cells remained refractory to the label (C). The outline of the cells as delineated by _vß₃ antibodies is depicted by a dashed white line. Images shown are representative of 50 osteoclasts and lateral views of the cells taken with CSLM with a thickness of 1.008 µm. Scale bar, 10 µm.