Surface morphology of the inner sulcus and related epithelial cells of the cochlea following acoustic trauma.

When the organ of Corti is severely traumatized by intense (160 dB) blast waves, such that as much as 7 mm of Corti's organ is torn loose from the basilar membrane, the cells of the inner sulcus respond to the altered biochemical milieu of the endolymph by a profile elaboration of surface membrane, zeiosis and the development of numerous pseudopodia and microvilli. On the basis of our longitudinal study, this surface reaction appears to peak at approximately 10 days after trauma and may indicate that the inner sulcus cells are extremely active in the endocytosis of cellular debris. Signs of active changes on the surface of the inner sulcus cells occur immediately following trauma, and activity continues for as long as 30 days after exposure. The cells of Claudius, as well as other epithelial cells on the basilar membrane, are also capable of extreme membrane proliferation and mobility. Possible mechanisms for the unusual behavior and the role of the inner sulcus cells in the normal functioning cochlea are discussed.