Post-natal bone growth in the semicircular canals of the dog

Dogs from the same litter, divided into three groups aged 10, 25, and 50 days, received an intraperitoneal injection of tetracycline for two successive days. The temporal bones were fixed, embedded in methylmethacrylate, sectioned in to a single 100 microns thick section along the main axis of the anterior and lateral semicircular canals, grounded by hand to 30 microns and observed at UV light. The new bone tissue is laid down both at the endosteal and endochondral bone of the anterior and lateral semicircular canals. The bone deposition decreases with the age of the animal and earlier at the endosteum than at the endochondral bone.