Progressive degeneration in the cochlear nucleus after chemical destruction of the cochlea.

In the guinea pig, the organ of Corti and the spiral ganglion cells were destroyed by administering gentamicin into the inner ear. The antero-ventral cochlear nucleus (AVCN) was studied with electron microscopy 15 and 30 days after treatment. There does not seem to be a specific type of degeneration induced by the drug. For nerve terminals, a progressive degeneration occurred: after 15 days, clear and swollen boutons appeared and after 30 days an electron-dense type of degeneration was observed. The cell bodies of the AVCN did not seem altered infirming a rapid, direct or indirect, neurotoxic effect of the drug.