Jacobson's Organ

(redirected from Vomeronasal organ)
Also found in: Dictionary, Thesaurus, Medical, Acronyms, Wikipedia.
Related to Vomeronasal organ: Flehmen response

Jacobson's organ

[′jā·kəb·sənz ¦ȯr·gən]
(vertebrate zoology)
An olfactory canal in the nasal mucosa which ends in a blind pouch; it is highly developed in reptiles and vestigial in humans.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Jacobson’s Organ


(also vomeronasal organ), a separate division of the organ of olfaction in the majority of terrestrial vertebrates. It is named after L. Jacobson, the Danish anatomist and physiologist who discovered it in 1811.

In the embryonic period Jacobson’s organ is present in all terrestrial vertebrates, including humans, in whom it is reduced by the ninth month of intrauterine life. In amphibians the organ is an outgrowth of the olfactory sac. It is absent in some adult reptiles, including turtles, crocodiles, and chameleons. In lizards and snakes the organ is completely isolated from the olfactory cavity and communicates with the oral cavity. Birds do not have Jacobson’s organ. The organ is well developed in most mammals, although it is absent in adult cetaceans and in some chiropterans and primates.

The paired Jacobson’s organ of mammals is located at the base of the nasal septum and in the form of long tubules, the posterior ends of which are blind. Anteriorly, the ducts of the organ in some species (marsupials and rodents) open directly into the nasal cavity, but most often they lead into the parotid ducts, which open into the oral cavity from the palate and into the nasal cavity near the nasal aperture. The organ varies in size, for example, from 8–9 cm long in a bull to 17 cm long in a buffalo. It is lined with sensory epithelium containing specialized receptor cells whose processes form a special branch of the olfactory nerve—the vomeronasal nerve.

The function of Jacobson’s organ has not been fully studied. It is used by snakes and lizards during their search for prey and for a mate. The molecules of odorous substances are transmitted to the receptors of the organ by means of the tongue, with which the animals probe surrounding objects. In mammals the organ participates in the perception of odors that guide sexual behavior.


Bronshtein, A. A. Oboniatel’nye retseptory pozvonochnykh. Leningrad, 1977.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
2: Modified eyelid retractor used to measure the hei- ght of the opening of the vomeronasal organ from the floor of the nose.
Sniff driven When inhaled molecules activate nerve cells in the mouse's vomeronasal organ, the signals travel to the accessory olfactory bulb in the brain, then on to sites that connect to the hypothalamus and mediate fear, attraction and aggression.
As the oral ducts leading to the vomeronasal organs lay within the direct pathway of the retracted tongue, it is generally assumed that the tongue serves as the normal means by which chemical cues are delivered to the VNS in snakes (Kahmann, 1932, 1934; reviewed in Young, 1993).
As a test of this prediction, the presence or absence of steroid hormone receptors in the buccal cavity and/or vomeronasal organ could be empirically confirmed in a range of vertebrate species.
The incidence of the vomeronasal organ in 1000 human subjects and its possible clinical significance.
McDaniel, "The reason for this delayed response is another one of the catnip mysteries--it may be that the receptors in the vomeronasal organ need time to develop, or that the catnip response area in the brain may not fully develop until a kitten is eight to twelve weeks old."
To reach the conclusion, Rodriguez's team took tissue from the vomeronasal organ - a pheromone-detecting sense organ found in the nasal cavity of mice, and some other mammals - and searched for genes expressing possible smell receptors.
Dulac prompted the gender bending by disabling a key gene in the vomeronasal organ, also called Jacobson's organ.