There are about 5 million neurons in the olfactory epithelium, or about 5, 000 neurons for each of the 1, 000 different receptor types.

FORBES: Magazine Article

Working with rats, Axel and Buck pinpointed 1, 000 types of "olfactory receptors" located in the back of the nose, on a spot called the olfactory epithelium.

FORBES: Magazine Article