|Frontal section of nasal cavities of a human embryo 28 mm. long (Vomeronasal organ of Jacobson labeled at right)|
|Gray's||subject #223 996|
The Jacobson's organ, is part of the body that helps an animal smell things. It is found in many animals. It was discovered by Frederik Ruysch and later by Ludwig Jacobson in 1813. It is also called the vomeronasal organ or VNO. This body part is mainly used to detect pheromones, chemicals that carry information between individuals of the same species.
Its presence and functionality in humans was controversial, though most studies agree the organ regresses during fetal development. Many genes essential for VNO function in animals are non-functional in humans. Chemical communication does appear to occur among humans, but this does not necessarily imply that the human vomeronasal organ is functional.
- Salamanders perform a nose-tapping behavior to presumably activate their VNO.
- Snakes use this organ to sense prey, sticking their tongue out to gather scents and touching it to the opening of the organ when the tongue is retracted.
- The organ is well developed in primates such as lemurs and lorises, developed to varying degrees in New World monkeys, and underdeveloped in Old World monkeys and apes.
- Elephants transfer chemosensory stimuli to the vomeronasal opening in the roof of their mouths using the prehensile structure, sometimes called a "finger", at the tips of their trunks.
- Painted turtles use this organ to use their sense of smell underwater.
Some mammals, particularly felids (cats) and ungulates (which includes horses, cattle, and pigs among other species), use a distinctive facial movement called the Flehmen response to direct inhaled compounds to this organ. The animal will lift its head after finding the odorant, wrinkle its nose while lifting its lips, and cease to breathe momentarily.
Behavioral studies show the importance of the vomeronasal system in animals’ social networks and everyday activities. It is important in the role of reproduction and social networking has been shown in many studies.
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