The experimental production of deafness in young animals by diet / by Edward Mellanby.

  • Edward Mellanby
Date:
[1938?]
Catalogue details

Licence: In copyright

Credit: The experimental production of deafness in young animals by diet / by Edward Mellanby. Source: Wellcome Collection.

    19/32 (page 389)
    shorter experiments there may be serous labyrinthitis without large structural defects in the organ of Corti. There is also a suggestion from one result in the present work that serous labyrinthitis can be cured by adding vitamin A to the diet even after the bone overgrowth and nerve degeneration are advanced. It is likely, for instance, by analogy with the other experimental results that dog III (curative experiment) had developed serous labyrinthitis as well as nerve and bone changes at the end of the 15 weeks on a vitamin A-deficient diet. This dog received abundant vitamin A for the next 27 weeks and at the end of this period the cochlear neurone had almost completely degenerated. There was, however, little or no serous labyrinthitis nor was there any abnormality of the organ of Corti or sensory epithelium of the ampullae of the semi¬ circular canals. It would appear possible from this experiment that the addition of vitamin A, after a period of vitamin A deficiency, cleared up the serous labyrinthitis and so prevented the degeneration of the organ of Corti but did not prevent the process of destruction of the cochlear neurone. This possible explanation would be in keeping with the view that degeneration of the sensory epithelium of the labyrinth in these experiments is due to serous labyrinthitis and not to degeneration of the auditory nerve. Further experiments to settle this point are, however, necessary. Serous labyrinthitis is probably not so early a pathological develop¬ ment as bone overgrowth or nerve degeneration, although it is true that wherever bone hyperplasia and nerve degeneration are advanced (apart from the curative experiment of dog III) serous labyrinthitis exists. In early and slighter cases of bone and nerve abnormality there may be no serous labyrinthitis. This is best seen in experiments in which the cereal element of a vitamin A-deficient diet is replaced by potato. The amount of bone hyperplasia in such cases is comparatively small though definite, and the cells of the spiral ganglion are slightly degenerated, but there is little or no serous labyrinthitis and the cells of the end-organs are apparently normal (Fig. 126). Early changes in labyrinth due to dietetic abnormality. As some of the results, especially the bony overgrowth, were quite unexpected, the appearance in earlier stages of the abnormality has not so far been studied, although histological material is now being prepared from experiments of shorter duration. These early changes can, however, be well seen in a series of experi¬ ments in which the cereal portion of the diet was replaced by potato. The diets otherwise were as previously described. It has been already pointed