Relationship of gross cochlear potentials to hair cell pathology in the waltzing guinea pig

Electrophysiological recordings were made from the hearing organs of young waltzing guinea pigs of different ages. Age-related morphological changes in the cochleas of the same animals were studied with scanning and transmission electron microscopy. Results were compared with the results of studying the cochleas of normal guinea pigs of the same age. Waltzing guinea pigs are born with a hearing loss, as can be concluded from the magnitude of the whole-nerve action potential and their lower than normal summating potentials. However, their cochlear microphonics are nearly normal until the time in the degeneration process when hair cells start to disappear. This degeneration process begins at the tops of the hair cells and is evident upon electron microscopical examination of these structures.