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?]
Catalogue details

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.

    3/16 (page 137)
    With respect to the component structures of a tootli, Professor Owen commenced by observing, that in addition to tliose usually described and admitted, there were other substances entering into the composi- tion of teeth, and presenting microscopic characters equally distinct both from ivory, enamel, and cement, and from true bone, and as easily recognisable. One of these substances was characterized by being traversed through- out by numerous coarse canals, filled with a highly vascular medulla or pulp, sometimes anastomosing reticularly,—sometimes diverging, and frequently branching,—sometimes disposed nearly jiarallel with one an- other, and presenting more or fewer dichotomous divisions. The canals in many cases are surrounded by concentric lamellae, and thus resemble very closely the Haversian canals of true bone ; but the calcigerous tubes which everywdiere radiate from them are relatively much larger. The highly-organized tooth-substance just described differs from true osseous substance, and from the caementum, in the absence of the Purkingian corpuscles or cells. This structure is exemplified in the teeth of many fishes and of some of the Edentate Mammalia. Another component substance of tooth moi-e closely resembles true bone and cement, inasmuch as the Purkingian cells are abundantly scattered through it; it differs, however, in the greater number and close parallel arrangement of the medullary canals. This structure is exhibited in the teeth of the Megatherium, Mylodon, and other extinct Edentata. Mr. Owen then proceeded to describe the modifications of the above- mentioned dental substances in the teeth of different classes of the ver- tebrate animals, of which the following examples are selected. 1st. Teeth of Fishes.—With respect to this class, although the low- est of the vertebrate series, their tefth present in general the most highly organized condition, approximating most closely to the vascular character of true bone, and being in many species fixed by anchylosis or continuity of substance with the bones supporting them. It was in the teeth of fishes that, in recent times, the tubular struc- ture had been first recognised. Cuvier*, e. g. describes them as pre- senting three different structures, of which one kind (Jes comj'josees) are formed of an infinity of tubes, all united and terminated by a com- mon covering of enamel; of this kind he instances the tesselated teeth (dents en forme de pave), as tliose of Fays. Dr. Born also describes -what he terms the “ fibrous teeth of fishes,” as being composed of hollow fibres ]', and he compares these hollow filires, or tubes, to those which enter into the composition of the teeth of the Orycteropus, &c. The tubes here spoken of, as well as those mentioned by Cuvier, are sufficiently largo to be distinguished by the naked eye; they do not, however, form the constituent texture of the teeth instanced, but only the coarser part of that texture. They contain a vascular medulla, * begons (I’Anat. Comp. 2d ed. tom. iii. p. 209. t Hcusiiiger’s Zeitsclirift, B. i. p. 181. “ Die Fascrzalinc bestelien in ilirem Inneni aus liohlen Fasoni,” &c.