A TOPOGRAPHICAL ANALYSIS OF THE POSTNATAL BONE-GROWTH IN THE COCHLEA OF THE DOG

The distribution of post-natal bone deposition was examined in the coc hlea of 10-, 25-, 50- and 90-day-old dogs that had been intraperitonea lly injected with tetracycline (20 mg/kg) five days before sacrifice. The temporal bones were embedded in methylmethacrylate and sectioned i n a single mid-modiolar section 30 mu m thick. The post-natal bone dep osition occurs both on the periosteal surfaces and on the vascular can als of the endochondral layer until the age of 90 days. Scattered bone deposition is also shown on the endosteal layer of the three turns an d on the spiral lamina until the age of 25 and 10 days respectively. T he percentage extension of the osteogenetic fronts shows a higher valu e at the periosteal layer than at the endochondral or endosteal layers .