Autoradiographic evidence of the coordinaion of the genesis of Sharpey'a fibers with new bone formation in the periodontium of the mouse

Multiple injections of ³H‐proline over a period of ten days produced a series of radiolabelled appositional bands at sites of new bone formation. Appositional surfaces of periodontal alveolar bone not only contained parallel appositional bands but also a second series of bands oriented perpendicular to the appositional bands. The perpendicular bands were continuous with Sharpey's fibers of the adjacent periodontal ligament (PDL). Labelling over Sharpey's fibers frequently extended beyond the osteoblasts and into the PDL. This pattern of ³H‐Proline labelling suggests that new Sharpey's fiber are secreted simultaneouly with new bone deposition. The shape and polarity of adjacent PDL fibroblasts suggests that they may migrate away from the bone surface as they engage in Sharpey's fiber formation.