Practical pathology : an introduction to the practical study of morbid anatomy and histology / by John Lindsay Steven.

  • Steven, John Lindsay, 1858 or 1859-1909.
Date:
1887
Catalogue details

Licence: Public Domain Mark

Credit: Practical pathology : an introduction to the practical study of morbid anatomy and histology / by John Lindsay Steven. Source: Wellcome Collection.

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    capsules—the primary, which surrounds the whole group, and the secondary, which invests individual cells. The zone, in which these phenomena are observed, forms a narrow band with perfectly regular and parallel margins, which may be recognized by the naked eye as a thin blue line near the junction of cartilage and bone. Beneath the layer just described another very narrow zone, which to the naked eye has an opaque, yellow appearance, is observed. With the microscope it will be seen that in this layer a de- position of lime salts has occurred in the hyaline matter surrounding the groups of cartilage cells, but as yet no proper bony tissue has been developed. Beneath this band of ossiform tissue, as it has been called by Cornil and Ranvier, the true bone formation is observed. The carti- lage cells have disappeared from the longitudinal spaces, and their place has been taken by round-celled tissue and blood- vessels, which constitute the fetal medulla. In the trabecular bone corpuscles with canaliculi may now be seen, and in the medullary spaces osteoblasts may be observed applying them- selves to the trabecular surfaces and slowly elaborating the bony matrix around them. Normal subperiosteal ossification.—Ossification also occurs in the normal state beneath the periosteum. Under the periosteum in the foetus is found a layer of round or poly- gonal cells, resembling in all respects the foetal medulla. From the shaft of the bone small spicules project into this cellular tissue, and on the surface of these osteoblasts are seen slowly forming new osseous tissue. These appearances are not difficult to make out in good specimens, and they have been described at some length, because it is only by thoroughly appreciating and comparing them with what is seen in specimens of rickets that the changes in the latter condition can be recognized and understood. Ossification in rickets.—In normal ossification one of the
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