Tooth. Light micrograph of a section through the roots of a tooth, consisting of oval-shaped columns of dentin each with a central core known as the pulp cavity, where nerves and blood vessels are found. Dentin is a hard calcified material similar to bone. The dentinal roots are supported by the surrounding zone of collagen-rich periodontal ligament. This anchors the tooth in the bony jaw sockets and serves to resist forces placed upon the tooth while allowing for limited movement during development and in orthodontic procedures. Magnification: x36, when printed 10 centimetres high.