Fig. 4.

Bone compartment optimization. (a) Schematic representation of the bone compartment. (b) Micrograph of mature, multinucleated osteoclasts on the surface of the bone slice. The white arrowhead shows an osteoclast with a circular actin ring, characteristic of resorption pit formation. (c) Mature osteoclasts on top of a bone slice. The white arrowhead shows an osteoclast with a crescent shaped actin ring, characteristic of a resorption trench formation. Single channel images are showed on the right. Blue (Top) - DAPI; Green (Mid) - Actin; Red (Bottom) - Cathepsin K. Scale bar - 100 ​μm. (d) Toluidine blue staining of the surface of the bone slice after three days of culture. Several resorption events are seen throughout the bone slice. In the left inset resorption pits are visible while in the right inset an example of a trench is shown. Scale bar - 200 ​μm. (e) Schematic representation of osteoclast resorption activity. Osteoclasts are capable of stationary resorption (left) or resorption while moving through the bone surface (right), leading to the formation of resorption pits or trenches respectively.