The periosteum, endosteum, and Haversian canals would be the resources of pluripotent mesenchymal stem cells that initiate the formation with the healing tissues. The bridging callus witnessed on radiographs mainly arises through the periosteum. This article was reviewed and approved by an orthopedic surgeon as we area a large quality https://www.theorthopaedicandpainpractice.com/what-is-a-long-bone-fracture/