A three-dimensional reconstruction of the ruffled border of osteoclasts.

Osteoclasts of rat parietal bones were cultured and observed under the transmission electron microscope. The processes forming the ruffled border were studied three-dimensionally by a reconstruction method. After the observation of one plane (A-plane), serial ultrathin sections were made at right angles to the A-plane (B-plane). The processes of the ruffled border in the B-plane were reconstructed, based on the A-plane features, with Nikon Cosmozone 2S. The three-dimensional structure of the ruffled border of the osteoclasts was composed of two kinds of processes: one finger-like and the other plate-like. Both finger-like and plate-like processes branched from the stem processes projecting directly from the cell body. The long plate-like processes branched into secondary plates, extending perpendicularly to the bone surface.