ABSTRACT
The auditory system seems better equipped to deal with injuries in lower species than in mammals. In fish and amphibians, the inner ear will produce new sensory cells (hair cells) throughout their life and, consequently, injured cells can be replaced continuously. Birds lose this ability during embryonic development, but possess the capacity to replace the injured sensory cells by regeneration and thus maintain hearing function. In contrast, mammalian hair cell loss has always been considered irreversible.
