For many years it has been known by scientists that pheromones exist in most animal species. When emitted they have some effect on members of the same species. For example, pheromones produced by queen bees stall sexual development in other females, who then become workers.
Male mice emit pheromones that can promote the sexual development of nearby females.
In order for pheromones to be detected, a special organ, called the vomeronasal organ must be present. This organ is composed of a pair of small pits on the membranous skin inside the nostrils. To see a picture of the vomeronasal organ click here . They designed a special electrode that could be inserted into the pits of the VNO which could detect any electrical activity that would be assumed to occur following a chemical interaction. The electrode was first tested in the olfactory cleft and responses were recorded for substances such as mint and clove oil.