What are rods?
Rods are one of the two types of light-sensitive cells in the retina; the others are called cones.
There are around 125 million rods in the human eye, which are necessary for being able to see in dim light.
Unlike cones, there aren't different classes of rods for different wavelengths of light, so in dim light when just our rods are stimulated we see in black and white.
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