Coloured scanning electron micrograph (SEM) of a fracture through a tooth. At top is the enamel with the dentine (beige) below it. Tooth enamel, the outer layer of the tooth, is the hardest material in the human body. Dentine is a mineralised connective tissue that forms the bulk of the tooth. Within the dentine are dentine tubules (brown). The tubules carry nutrients from the inner pulp of the tooth, which contains the blood vessels and nerves, throughout the dentine. They also transmit sensations from the outside of the tooth to the inside. The picture was created as part of a cooperation with Quintessenz Publishing. Magnification: x20,000 when printed at 15cm wide.