Histological studies of electrically induced intramedullary callus

The author studied the early changes of electrically stimulated bone marrow and carried out histological examinations. A constant current of 10 microAmp was delivered to the cathode which was placed in the humerus of each rabbit. On the 5th, 14th and 21 st day, the rabbits were killed, and the intramedullary tissues around the tip of the cathode were processed for light and electron microscopic observations. In the early stages after electrical stimulation, the leakage of erythrocytes, membranocystic degeneration of lipid cells, and proliferation of undifferentiated mesenchymal cells with moderately developed rER and collagen bundles were recognized. These findings indicate that the oxygen tension around the cathode was diminished in advance of the electrically stimulated callus formation. After prolonged electrical stimulation, both membranous and endochondral ossifications were more active than those in the control group.