A topographical analysis of the post-natal bone growth in the cochlea of the dog

The distribution of post-natal bone deposition was examined in the cochlea of 10-, 25-, 50- and 90-day-old dogs that had been intraperitoneally injected with tetracycline (20 mg/kg) five days before sacrifice. The temporal bones were embedded in methylmethacrylate and sectioned in a single mid-modiolar section 30 microns thick. The post-natal bone deposition occurs both on the periosteal surfaces and on the vascular canals of the endochondral layer until the age of 90 days. Scattered bone deposition is also shown on the endosteal layer of the three turns and on the spiral lamina until the age of 25 and 10 days respectively. The percentage extension of the osteogenetic fronts shows a higher value at the periosteal layer than at the endochondral or endosteal layers.