In mammals, glomeruli typically range between 50-120 μm in diameter and number between 1100 and 2400 depending on the species, with roughly between 1100 and 1200 in humans.

[2] Glomeruli are important waystations in the pathway from the nose to the olfactory cortex and have been found to be critical for odorant signal transduction.

The glomerular activation patterns within the olfactory bulb are thought to represent the quality of the odor being detected.

Linda Buck and Richard Axel were awarded a Nobel prize in 2004 for heavily influencing the working out of the genetic basis for this Olfactory coding.

Thus, a glomerulus representing a specific OR develops slowly and involves considerable axonal reorganization in order to achieve the highly topographical projection observed in adult mice.

Some dogs have as many as 100 times more ORNs than humans do, producing a correspondingly sharpened ability to detect and discriminate among millions of odors.

[12] One of the most distinctive features of fish olfaction is that it takes place entirely in the aquatic environment.