Coloured scanning electron micrograph (SEM) of dentin (substantia eburnea), the mineralised connective tissue found under a tooth's enamel. The pulp, the soft tissue containing nerves and blood vessels that makes up the inner part of the tooth, has been removed to reveal the yellow mesh of new and partially formed dentine (top). Also seen are the dentinal tubules (dental canaliculi) in the dentin (bottom). These are minute holes that have been formed by the cytoplasmic extensions of odontoblast cells (dentine-producing cells). The odontoblast cells originate in the pulp and allow the dentine to rebuild itself. Magnification: x833 when printed 10 centimetres wide.