Histological and histochemical investigations of constant direct current stimulated intramedullary callus.

A morphometrical study of the intramedullary callus directly stimulated by electricity was carried out to clarify the relation between callus formation and locus of the cathode. A histochemical study of the cells which appeared in the bone marrow after electrical stimulation indicated promotion of osteogenesis by electrical stimulation by direct activation of osteoblast differentiation. The author used alkaline phosphatase (ALP) activity as a marker of osteoblast. Electrically induced callus formation increased significantly within 0.5 cm of the tip of the cathode. The callus encircled the cathode in a cylindrical fashion at the tip of the cathode. No callus formation from the endosteum was observed. Under histochemical investigation, although the cell morphologically regarded as the osteoblast revealed strong ALP activity on the cell membrane and the Golgi apparatus, mature osteocytes revealed no activity. These findings support the view that electrical stimulation promote osteoblast differentiation.