Effects of endolymphatic and perilymphatic application of salicylate in the pigeon. II: Fine structure of auditory hair cells.

Large doses of salicylate are known to cause reversible ototoxic effects including fine structural alterations of the auditory hair cells in mammals. To investigate possible fine structural correlates of salicylate effects on pigeon auditory hair cells, the basilar papillae following perilymphatic or endolymphatic application of salicylate were fixed and processed for transmission electron microscopy. The pigeon auditory hair cells possessed organelles typically described in avians. A single or multi-layered array of cisternae along the cytoplasmic side of the lateral plasma membrane, i.e. subsurface cisternae that are characteristic for mammalian outer hair cells, was not seen. The most prominent fine structural alterations of hair cells after salicylate application were an increase in the luminal width of smooth and rough endoplasmic reticulum as well as the frequent occurrence of prominent single-membrane-bound vesicles filled with electron-dense bodies. Based on the assumption that subsurface cisternae represent a specialized form of endoplasmic reticulum, the present findings indicate that the structural correlates of salicylate toxicity are similar in mammalian and avian auditory hair cells.