Method for tracing single fibers in the organ of Corti with horseradish peroxidase.

A method based on the axonal transport of horseradish peroxidase (HRP) has been developed to trace single fibers in the organ of Corti. HRP was injected into the auditory nerve or cochlear nucleus of the adult chinchilla, and the entire cochlea was subsequently incubated for reaction product. Of most significance was the Golgi-like labelling of single radial afferents innervating the inner hair cells. Heretofore, radial afferents have been difficult to trace with more conventional staining techniques, especially in adult animals. Outer spiral fibers, presumably afferent, were also labelled in one of the cochleas.