Appearance of osteoclasts and osteoblasts in electrically stimulated bones cultured on chorioallantoic membranes

Tibial shafts from 15-day-old chick embryos were cultured on chorioallantoic membranes of chick embryos. These bones were stimulated by either constant-direct or constant-alternating current via platinum wire electrodes. Around the anodes of 10 microA constant direct-current stimulation, the number of osteoclasts was significantly larger than that of the control, and numerous osteoblasts were observed. Around the cathodes of this current, periosteum was thickened and accompanied by proliferation of osteoblasts. Slight bone resorption in the immediate vicinity of the cathodes was also observed. The periosteum between the two electrodes was significantly thickened by this current. The comparative study between equivalent constant direct-current and alternating-current stimulation showed a dominance of direct current. This model could be useful in investigations on electrical stimulation of bone in vivo. It produces fewer artifacts and shows activation of osteoclasts in association with activation of osteoblasts in electrically induced reactions of bone tissue.