On the structure of teeth, and the resemblance of ivory to bone, as illustrated by microscopical examination of the teeth of man, and of various existing and extinct animals / by Professor Owen.
- Owen, Richard, Sir, 1804-1892.
- Date:
- [1838?]
Licence: Public Domain Mark
Credit: On the structure of teeth, and the resemblance of ivory to bone, as illustrated by microscopical examination of the teeth of man, and of various existing and extinct animals / by Professor Owen. Source: Wellcome Collection.
Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.
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![niosing and communicating with minute calcigcrous cells immediately beneath the enamel. 4 he teeth of those orders of Mammalia in which they present the usual structure of compact ivory, enamel, and cccmentum, have been described in several genera with so much accuracy by Professor/fetem.s, that there are few modifications or examples worthy of particular at- tention. In the simple teeth of the Marsupial animals, the external layer of ccamentum covering the enamelled crown is thicker in many of the species than is usually seen. The Phalangers, Koala, and Wombat, offer good examples of the superficial layer of cement on the exposeil crown. It possesses the usual high degree of organization, and abounds in the Purkingian cells. In the incisors of the Orang-Utan, the main calcigcrous tubes of the ivory, which radiate from the central cavity of the pulp, are somewhat larger than those of man; they present the same primary curvatures, but less numerous and less strongly-marked secondary undulations*. In the crown of the tooth of the Orang, the dental tubes are chiefly branched at their extremities, while towards the apex of the fang the main tubes are surrounded by exceedingly fine and close-set branches, which subdivide in their course. 'I'he nearer the crown, the larger are these branches; they are curved, with the concavity towards the pulp. In the summary of this series of observations which Professor Owen detailed, he observed, that in the human and similarly organized teeth, the analogy of ivory to bone, as to texture, was only seen in the ex- istence and intercommunication of the minute calcigcrous tubes and cells; but that there was no trace of medullary or Haversian canals, with their characteristic concentric laminae, unless the entire tooth wei’e regarded as analogous to a single enlarged Haversian canal, when the cavity of the simjile pulp would represent the medullary cavity of the canal; while the tubes, with the appearance of laminm occasioned by their undulations, might be deemed equivalent to the concentric la- mellae and the calcigcrous tubes, xvhich, in bone, traverse these lamellae, and radiate from the Haversian canal. In the teeth of many of the lower animals, however, and especially that of the extinct Acrcdits, amongst the cartilaginous fishes, the resemblance of the dental tissue to bone was extended to the existence of the characteristic Haversian canals in great numbers. The presence of these canals was explained by the progress of the development of these bone-like teeth, as observed by Professor Owen in recent cartilaginous fishes. The large pulp, at the commencement of the formation of the tooth, had exercised its ordinary function in the secretion of a close-set series of calcigcrous * The primary curvatures Professor Owen explained to he those which belong to the general course of the dental tube, and which are seen with a lower power; in man tlicy resemble the curves of the Greek Zeta (?). The secondary curves are mi- nute undulations in the whole course of the tube, requiring a high power for their ])erception, and allecting both the main trunks and tlicir branches; these i)robably indicate and arc due to the movements of the formative pulp during the deposition of the ivory.](https://iiif.wellcomecollection.org/image/b2239087x_0016.jp2/full/800%2C/0/default.jpg)
