Inner stereocilia from Guinea pig cochlea. Scanning electron micrograph view of stereocilia in inner cell hair bundle, showing links between shorter stereocilia in 2nd & 3rd rows and taller ones in next row. These are thought to detect mechanical movement in response to sound by being alternately stretched and relaxed as the hair bundle vibrates. Stetching may open ion channels in membrane, increasing current. Magnification X 74,000. Supplied by Dr Spiro Comis, courtesy of Wellcome Images.