Our teeth, how built up, how destroyed, how preserved / described and illustrated by R. Denison Pedley, and Frank Harrison.

  • Pedley, R. Denison (Richard Dension)
Date:
1908
Catalogue details

Licence: In copyright

Credit: Our teeth, how built up, how destroyed, how preserved / described and illustrated by R. Denison Pedley, and Frank Harrison. Source: Wellcome Collection.

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    a ridge along the rudimentary jaw. A vertical line indi- cates the spot where a portion of this epithelial layer has grown into the jaw. Below, it has expanded into a bell- like structure—the enamel organ. Ten of these enamel organs are found in each jaw. Each enamel organ is met by a small mound from the deeper tissue, growing upwards and shaping the cap of epithelial cells; this is the dental germ. By the side of this embryo temporary tooth is a vertical line of cells which has grown down in the form of a wavy tube; this will eventually become the enamel organ of a permanent tooth. A section through an embryo jaw at a later stage, as in fig. 7, shows that remarkable changes have taken place. The vertical band by which the enamel organ was attached to the gum has disappeared. The rudi- mentary tooth is isolated. Enclosed in a membrane—the dental sac—the enamel organ and the dental germ are more highly organized. Fig. 8 shows a portion of the same structure greatly magnified. The shape of the tooth is de- termined. The three layers of cells which form the cap of enamel are undergoing rapid change. Surrounding the apex of the dental germ is a clear space. Immediately below this is a layer of cells, cylindrical in form, with well-marked nuclei. These facts may be rendered still clearer if it can be realized that the pictures are actual stages in the life- history of what was at one time living tissue. It is recorded of the ancient city of Pompeii—buried so Ions: beneath the ashes of Vesuvius—that when death came the soldier was found at the post of duty, the workmen were constructing their buildings, and the citizens attending to their daily occupations. The sections in figs. 6 to 9 may be regarded as records of the past, as small portions of a buried city. The finished buildings will be seen later. We have in the previous de- scription endeavoured to trace the ground plan, to see how the foundations are laid, and to form some conception of how the walls are built. Now we have reached a point at which we can see the workmen engaged in building up the tooth. The