Fig. 1. The actin cytoskeleton in chicken osteoclast precursors during in vitro osteoclast differentiation. After an initial trypsinization (see Materials and Methods), macrophagelike cells were cultured on glass coverslips for one day (left panel) or for additional four days in the absence (middle panel) or presence (right panel) of RANKL-ODF. Subsequently, cells were fixed, permeabilized, stained with rhodamine-phalloidin and photographed on a Zeiss immunofluorescence microscope. Note the profound changes in the cellular distribution and in the density of podosomes. Scale bar: 10 µm.