The anatomy of the central nervous organs in health and in disease / by Heinrich Obersteiner ; translated, with annotations and additions, from the third German edition, with all the alterations and corrections prepared by the author for the forthcoming fourth German edition by Alex Hill.
- Heinrich Obersteiner
- Date:
- 1900
Licence: In copyright
Credit: The anatomy of the central nervous organs in health and in disease / by Heinrich Obersteiner ; translated, with annotations and additions, from the third German edition, with all the alterations and corrections prepared by the author for the forthcoming fourth German edition by Alex Hill. Source: Wellcome Collection.
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![PROGRESS OF DEGENERATION. activity, their protoplasm accumulates, their fatty metabolite is absorbed; their nuclei increase in size, develop regular active chromatin skeins and initiate cell-division. This condition of sur-activity soon begins to wane, accumulation of protoplasm ceases, the cells shrink and assume a stable form. Finally, the degenerated nerve comes to resemble a cord of connec- tive-tissue. A nerve-fibre has essentially the same structure whether it occurs within or without the axis. It consists of the real fibre, the cell-process or axis- cylinder, invested by myelin-cells, each of which is a hollow cylinder filled with phosphatic fat. While within the axis fibre and myelin-cells are sup- ported by a neurogleia-sheath. When running through mcsoblastic tissues, they are invested with a connective-tissue sheath, the sheath of Henle. A peripheral nerve completely loses its irritability (in a warm-blooded animal) within forty-eight hours after section. Even by this time a distinct change is visible to the naked eye. Owing to the already-commencing accumulation of protoplasm in the medullary sheath, at first about the nuclei, with coincident absorption of myelin, the fibre looks less solidly white, and glistening. In about twenty days (Ranvier) the myelin only remains in drops, which here and there distend the sheath of Schwann. Within the fresh cord a degenerated area is recognisable by. the fifth week after injury as a milky patch. In three or four months it becomes less white, then grey, transparent and gelatinous in appearance (Sherring- ton). Finally, it is indistinguishable until after hardening of the cord. In the cord, hardened in bichromate of potassium, the degenerated area is visible at an earlier stage than in the fresh cord (in the cervical and dorsal regions in nine days—Sherrington) as an area lighter in colour and yellower than the surrounding white matter. For about the first six months after injury the distinctness of the degenerated tract increases. After this time it begins to shrink. In sections stained with carmine or acid fuchsin degenerative changes can be recognised in about a week (in the posterior columns in three days, in the lateral pyramidal tract in five, in the direct cerebellar tract in seven—Hombi). At first the axis-cylinder appears thicker than normal and granular, and stains less darkly with carmine and more darkly than normal with acid fuchsin. The myelin-sheath begins to stain, especially at its inner part, more distinctly with carmine and less dis- tinctly with acid fuchsin or Weigert’s hematoxylin. Absorption of fat and proliferation of the myelin and neurogloia cells then ensues, in the same manner as already described for peripheral nerves. In a carmine-stained section the degenerated area is recognisable for a long period with a low power as a dark red patch, although its power of staining gradually diminishes.] (cl.) Essentially different to the methods we have just been describing is the plan introduced by Gudden, which also has yielded important results. There are points of similarity certainly between this method and the method of secondary degeneration; but in Guddcn’s method lesions are produced only on new-born animals (rabbits, puppies, and kittens). In such subjects the nervous system is still in a partly-embryonic condition,](https://iiif.wellcomecollection.org/image/b28716826_0060.jp2/full/800%2C/0/default.jpg)
