Development of a Tooth

Diagram to illustrate the development of a tooth. I. Shows the downgrowth of the dental lamina D.L. from the surface epithelium E and the beginning of the enamel germ E.G. II. Shows the further growth of the enamel germ and its invagination. III. The enamel germ is more invaginated, and its inner layer of cells becomes columnar. A, the dental lamina, grows thinner, but near its posterior or lingual edge there is an enlargement R.G which is the reserve germ for a permanent tooth. The superficial cells of the dentine papilla P are becoming columnar. IV. The inner columnar cells of the enamel germ ( called enamel cells) A have formed a cap of enamel EN, inside which the superficial cells of the papilla, the odontoblasts O, have formed a layer of dentine D. V. Shows a more advances stage still. The deposit of dentine is extending downwards, and enclosing the papilla to form the future pulp, in which a vessel V is seen. Labels: A, inner layer; B, outer layer; C, remains of intermediate cells; D, dentine; D.L, dental lamina; E, epithelium; E.G, enamel germ; EN, enamel; F, dental furrow; L.D, labio-dental furrow; M, connective tissue cells; O, odontoblasts; P, dentine papilla; R.G, reserve germ; V, blood vessels.

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