Answer:
The inner hair cells are on the right side of the first two photos. They are about 3,500 in number. Each has a single row of 50 to 60 microvilli. The outer hair cells are about 20,000 in number and occur in three parallel rows along a spiral ribbon that coils from the base to the apex of the cochlea. In spite of their greater number and fancier, prettier appearance, we can’t hear anything that comes from the outer hair cells. Everything we hear comes from the inner hair cells.
