Fig 2.
(Upper) Hair bundle of a normal, immature (postnatal day 4) mouse outer hair cell showing the V-shaped array of stereocilia (arrowhead) on the outer side arranged in staircase-like rows of graded heights and microvilli (arrow) on the inner side that will be resorbed later. (Lower) Top of an outer hair cell from a postnatal day-4 waltzer mutant (Cdh23v2J/Cdh23v2J) showing that stereocilia (arrowhead) have grown tall and formed clusters with rows of graded heights, whereas microvilli (arrow) are present but will be resorbed later. Both hair cells are from the middle row of the three rows of outer hair cells and from a region 20% of the distance from the apex of the cochlear duct. (Bar, 2 μm.) The figure was kindly provided by Ralph Holme (Nottingham, U.K.).