Matrix collagen of devitalized bone is resistant to osteoclastic bone resorption

The resorption of devitalized bone by isolated osteoclasts in culture was studied by scanning electron microscopy. Osteoclasts attached to the bone and resorbed mineral but left most of matrix collagen undigested in the resorption pits. Postculture-treatment of bone substrate with collagenase completely removed the matrix collagen in the resorption pits, whereas trypsin did not. The results suggest that native matrix collagen is resistant to osteoclastic attack in this in vitro model using devitalized bone.