Light microscopy of a early phase of tooth development in the fetus. The epithelial surface of the oral cavity at right is extended inwardly into forming a curvature resembling a cap overlying a core of tissue, the dental papilla, hence the designation as the cap phase. The epithelial cap will develop into cells forming enamel beneath which cells derived from the papilla will produce dentin. The dental papilla which has blood vessels and nerves, eventually becomes the pulp cavity or root canal. Magnification x85 when printed at 10 cm.