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.

    18/32 (page 388)
    Serous labyrinthitis in man is also associated with a series of degenera¬ tive changes in the organ of Corti and the sensory epithelium of the vestibule. Similar changes take place in the animals under discussion. Degenerative changes in the organ of Corti. In serous labyrinthitis in man, one of the earliest changes in the organ of Corti is the loss of differential staining power between cytoplasm and nuclei in the cells of the rods of Corti and in the outer and inner hair cells. This change cannot be seen in the histological preparations so far made in the present work, probably because the technique used is not suitable. In severer cases of experimentally produced serous labyrinthitis, the degeneration of these cells becomes more marked, the hair cells lose their hairy projections and ultimately these auditory cells, as well as Deiter’s and other cells of the organ of Corti disappear, leaving a small amount of undifferentiated tissue lying on the basement membrane (Fig. 5). In spite of the degenera¬ tion of these cells, there still remains the small tunnel of Corti. In Fig. 3, representing the organ of Corti of a dog receiving vitamin A, the structure is normal. Degenerative changes in the epithelial cells of the ampullae. Up to the present time a comparative study of the vestibular apparatus has not been made but changes in the epithelium of the semicircular canals in those animals fed for long periods on A-deficient diets are also obvious. Com¬ paring Figs. 16a and 166 (vitamin A deficient) with Figs. 15a and 156 (receiving vitamin A), it will be seen that there is a general thickening of the epithelium in the former. Associated with this thickening there is a loss of differentiation of the individual cells, the disappearance of the nuclei and a shedding of hairy projections. Relation of serous labyrinthitis to end-organ degeneration. When the degenerative changes in the organ of Corti and in the sensory epithelium of the vestibule above described were first noted, it was thought that these might be due to degeneration of the cochlear and vestibular nerves respectively. Dr Hallpike informed me, however, that this was not the case, since there was good evidence that cutting the 8th nerve, although it produced degeneration of the whole cochlear neurone, did not produce degenerative changes in the organ of Corti. He also informed me that serous labyrinthitis in man ultimately affected the organ of Corti and the sensory epithelium of the ampullae. It seems likely, therefore, that this is the sequence of events in the present experiments. Serious structural changes in the organ of Corti are a late event compared with the nerve degeneration and bone hyperplasia and appear always to be accompanied by serous labyrinthitis. On the other hand, in