Scientists have created a first-hand map of smell receptors in the mouse nose, revealing that these receptors are highly organized and separated into tight bands. The study, published in the journal The Journal, revealed that each neuron expresses one of 1,172 different receptors encoded in mouse DNA, each receptor detecting a different type of smell. The map also identified a molecule called retinoic acid (RA) that likely guides each neuron to express the correct receptor based on the location. The discovery could help develop treatments for loss of smell and its consequences, including those of human nose.