The Beauty of Hearing

What am I looking at?

To study the cells of this cochlea, researchers extracted it from a newborn mouse and grew it in culture. The cochlea itself is the blue spiral at the center of the image (1). The neurons that send auditory information from the cochlea to the brain can be seen in orange (2). And the green and white dots surrounding the cochlea (3) are the nuclei of surrounding cells.

Biology in the background

The cochlea is a fluid-filled, spiral-shaped sac in the inner ear. Its interior surface is lined with hair cells that detect fluid movement. When sound waves hit the eardrum, they cause the eardrum to vibrate. This vibration travels through several very small bones in the inner ear that connect to the cochlea. The vibration of these bones causes the fluid inside the cochlea to move, mimicking the sound waves in the air outside the ear.

The movement of the fluid in the cochlea moves tiny projections, called stereocilia, that extend from the hair cells lining the inner surface of the cochlea. These hair cells then pass the signal on to neurons in the inner ear that send projections to the auditory centers of the brain, where sounds are processed.

If you unrolled a mouse cochlea, it would be about 6 millimeters long, or roughly four times smaller than the width of a human thumbnail.

Technique  

This image was created using confocal microscopy.