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Enamel is composed of fine hexagonal fibers which are set on end on the surface of the dentine and fit into corresponding depressions. Shown is a thin section of enamel and a part of the dentine. Labels; a, cuticular pellicle of the enamel (Nasmyth's membrane); b, enamel fibers, or columns with fissures between them and cross striae; c, larger cavities in the enamel, communicating with the extremities of some of the dentinal tubuli.

Section of the Enamel

Enamel is composed of fine hexagonal fibers which are set on end on the surface of the dentine and fit…

The first step in the development of teeth consists in a downward growth from the Rete Malpighi or the deeper layer of stratified epithelium of the mucous membrane of the mouth, which first becomes thickened in the neighborhood of the maxillae now in the course of formation. This development is shown in a section of the upper jaw of a fetal sheep. A- 1, common enamel germ dipping down into the mucous membrane; 2, palantine process of jaw; 3, Reta Malpighi. B- Section similar to A, but passing through one of the special enamel germs here becoming flask-shaped; c, d, epithelium of mouth; f, neck; f', body of special enamel organ; p, papilla; s, dental sac forming; f p, the enamel germ of permanent tooth; m, bone of jaw; v, vessel cut across.

Development of Teeth

The first step in the development of teeth consists in a downward growth from the Rete Malpighi or the…