Observations on the structure and development of bone / by John Tomes and Campbell de Morgan.

  • John Tomes
Date:
[1853]
Catalogue details

Licence: Public Domain Mark

Credit: Observations on the structure and development of bone / by John Tomes and Campbell de Morgan. 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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    a transverse section of the latter the parietes are readily recognized, as shown in figure 11, Plate VII. In a longitudinal section of Haversian systems we have the laminae on either side of the canals cut at right angles, or nearly so, while immediately over the canals they are exposed in their breadth ; in the one instance we look upon the cut edges, in the other upon the surface of the laminae. The lacunae in the two parts present dif- ferences in outline. In the former part they resemble those seen in the Haversian systems divided transversely, in the latter they approach a circular, or slightly oval figure, and send out canaliculi indifferently from all parts of their circumference. After examining the lacunae from these three different points of view, it will be mani- fest to the observer that the normal form is that of a greatly compressed hollow sphere or oval, from which numerous minute tubes are continued. To this prevailing form we find numerous exceptions, which, although of not unfrequent occurrence, form but a small part of the whole number that may be seen in an ordinary prepara- tion. The outlines assumed by the exceptional lacunae are too varied and too irre- gular to admit of such a description as would embrace every departure from the ordinary form. It is however worthy of mention, that lacunae may sometimes be met with, normal in form, but of three times the usual dimensions. What has been said of the lacunae of the Haversian systems will of course apply also to those occupying parts of systems known under the name of interstitial laminae. In the circumferential laminae the lacunae are for the most part similar to those already described. But we have in this situation what may perhaps be regarded as modified lacunae, presenting themselves in the form of elongated tubes arranged in bun- dles, or occurring singly, and passing more or less obliquely from the surface towards the interior of the bone (Plate VII. fig. 13). When these tubes attain a considerable length they are commonly bent at a sharp angle once or twice in their course, and at each flexure change their direction, presenting sometimes a loose resemblance to the letter 2. When these tubules are divided transversely they exhibit parietes. On tracing them in parts abounding with lacunae, it will be seen that they form lateral connections with the canaliculi, at the same time that they cross these as well as the lacunae and laminae obliquely. The presence of the oblique tubes is not however con- stant. In one part of the circumferential laminae they will be abundant, while in another they will be sparingly present or altogether absent. Then, again, they may be seen in one series of laminae, while in the contiguous set they are absent, but may reappear in a third and more deeply-seated series. They are, however, we believe, strictly confined to the limits of the circumferential laminae, and are seldom present unless these are tolerably abundant. The lacunae situated in the transparent non-laminated bone, which is sometimes found on or near the surface, and to which we have before alluded, are less com- pressed in form than those hitherto described. They are subject to great irregularities of outline, and send off canaliculi equally from all parts of their circumference, thereby
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