Tooth enamel formation. Coloured scanning electron micrograph (SEM) of a freeze-fractured section through a tooth, showing the enamel-forming cell layer (bottom half of image). The fracture plane is parallel to the tooth's enamel surface, the undersurface of which has been exposed in the top half of the image by removing the enamel-forming layer. This epithelium comprises a single layer of columnar cells called ameloblasts. Their round and regular transverse sections are seen. They are embedded in the enamel, creating the pattern seen in the exposed enamel layer across top. Enamel is a hard ceramic layer that covers and protects the teeth. Magnification unknown.