Lesions of the central and peripheral nervous systems produced in young rabbits by vitamin A deficiency and a high cereal intake / by Edward Mellanby.

  • Edward Mellanby
Date:
[1935?]
Catalogue details

Licence: In copyright

Credit: Lesions of the central and peripheral nervous systems produced in young rabbits by vitamin A deficiency and a high cereal intake / by Edward Mellanby. Source: Wellcome Collection.

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    Dye [14] met the same difficulties. He found that chromolytic reaction in nerve-cells follows the same general course in conditions of such diverse symptomatology as parathyroid tetany and cretinism, and decided that chromolysis is a reaction of nerve-cells initiated by any factor which opposes the normal physiological equilibrium of these units, a conclusion similar to that reached years ago by Van Gehuchten.1 In primary degenerative changes, as pointed out by Van Gehuchten [15], the Nissl bodies or chromophile particles do not, as a rule, undergo real chromolysis. When altered in this direction there is no real dissolution of the chromophile substance, but rather an achromatosis or partial disappearance or change of chromophile elements in some part of the cell. Marinesco states that, when the lesions are primary, chromolysis commences in the periphery of the nerve-cells and spreads towards the centre, whereas in secondary or traumatic degeneration the chromolysis begins centrally and spreads towards the periphery. In the present investigations the changes in the nerve-cells can be classified among the primary or toxic group, although produced by ordinary foodstuffs without the addition of any known toxic agent. On the whole, but not absolutely, Marinesco’s generalisation as to the peripheral location of changes in the Nissl bodies in primary degeneration applies to the present results, although there are some exceptions. Beal chromolysis (in the sense used by Nissl) is not very common, and when present generally affects a small portion of the cell either at the periphery or near the nucleus. A few instances of chromolysis comparable to that seen in secondary degeneration were found, more especially in certain cells of the medulla. More often the granules lose their discrete form and are in a powdery or lightly staining condition, the parapyknomorphic change of Nissl. At times the Nissl bodies may be aggregated into clumps, and in other cases they may be so changed that the cell takes on a more intense, even stain and is described as chromophile. In addition to degenerative changes in the cytoplasm, the nucleus and nucleolus are often affected. They may be swollen or shrunken. Sometimes the nucleus leaves the centre of the cell and becomes eccentrically placed. Occasionally the nucleus seems to have disappeared or its space to be invaded by the cytoplasm with Nissl bodies. At times the nucleus may appear finely granular instead of clear as it is normally. 1 For discussions of the various hypotheses concerning chromolysis in damaged nerve cells see Van Gehuchten, Anatomie clu Systeme Nerveux, de Vhomme, 1900, Vol. 1, pp. 313-339; also S. Bamon-y-Cajal, Histologie du Systeme Nerveux, 1909, Vol. 1, pp. 214-222.