Inner ear hair cells. Coloured scanning electron micrograph (SEM) of hair cells in the organ of Corti. This delicate structure in the cochlea of the inner ear converts sound vibrations into nerve impulses. The three rows of outer hair cells have V-shaped groups of stereocilia (red), while the single row of inner hair cells is shown by a line of stereocilia. The hair cells sit between two membranes (neither seen) in endolymph fluid. Sound vibrations transmitted from the perilymph fluid of the middle ear into the endolymph cause the hair cells to compress, generating nerve impulses that are carried to the brain. Magnification unknown.