Title: Compendium of histology
Identifier: compendiumofhist00frey (find matches)
Year: 1876 (1870s)
Authors: Frey, Heinrich, 1822-1890; Cutter, George R. (George Rogers), b. 1840, tr
Subjects: Histology
Publisher: New York, G. P. Putnams sons
Contributing Library: Boston Public Library
Digitizing Sponsor: Boston Public Library

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sesses—and at a later stage as well—a similar cell covering. These (Fig. 67, b), are the dentinal cells or, as they have been characteristically named (Waldeyer), the odontoblasts, the sculptors of the tooth bone. Our cells, oblong, measuring 0.02 to 0.03 mm., are stra- tified. One or more of their fine, thread-like processes penetrate the dentinal tubuli peripherically. An able English investigator, Tomes, first saw such " soft fibres " here. The crown is covered with enamel, the hardest substance of the body. The organic form-deter mining basis amounts to only a slight per cent. (3.5 to 6), against a prodigious excess of bone earths. The enamel (Fig. 68), a petrified epithe- lial production, consists of long, closely crowded polyhedral cylinders, the enamel prisms or enamel columns (b). They fre- quently appear to pass through the entire thickness of the enamel covering; their di- ameter is 0.0034 to 0.0045 mm. Transverse polished sections of the enamel show a delicate hexagonal mosaic (Fig. 69). A peculiar transversely striated appearance may be recog- nized in the isolated enamel prisms. The surface of the enamel, finally, is cov- ered by an uncommonly tough membrane. This is the cuticle of the enamel (Fig. 68, a). Beneath the enamel the dentinal tubules form loop-like and reticular transitions (Fig. 68, d). In the hard brittle substance of the former, there has been a formation of numerous clefts (c), which may communicate with the canals of the dentine. With the tolerably simple structure of the teeth, which has y. Fig. 68. — Peripheral portion of the dentine d, from the crown; with enamel covering,/': a, enamel membrane ; c, the cavities filled with air.
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Fig. 69. — Transverse section of the human enamel prisms.

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