Jacobson's organ

Jacobson's organ
/jay"keuhb seuhnz/, Anat., Zool.
either of a pair of blind, tubular, olfactory sacs in the roof of the mouth, vestigial in humans but well-developed in many animals, esp. reptiles.
[1870-75; named after L. L. Jacobson (d. 1843), Danish anatomist]

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also called  vomeronasal organ 

      an organ of chemoreception that is part of the olfactory system (smell) of amphibians (amphibian), reptiles (reptile), and mammals (mammal), although it does not occur in all tetrapod groups. It is a patch of sensory cells within the main nasal chamber that detects heavy moistureborne odour particles. Airborne odours, in contrast, are detected by the olfactory sensory cells located in the main nasal chambers. Some groups of mammals also initiate a behaviour known as the flehmen response, in which the animal facilitates the exposure of the vomeronasal organ to a scent or pheromone by opening the mouth and curling the upper lip during inhalation.

      This organ was named for its discoverer, Danish anatomist Ludvig Levin Jacobson, in 1811. It is a paired structure; in the embryo stages of all tetrapods, each half arises as an evagination of the floor of a nasal sac. In fully developed crocodilians (crocodile), turtles (turtle), birds (bird), cetaceans (cetacean), and many advanced primates (primate), this structure is absent or substantially underdeveloped. For most tetrapods that possess a Jacobson's organ, ducts connect the organ directly to the nasal cavity; however, in squamates (lizards (lizard) and snakes (snake)) each organ opens on the roof of the buccal cavity (mouth). The tongue carries odour particles from the outside to the vomeronasal openings on the roof of the mouth, and the particles then move into the vomeronasal organ. After these particles reach the organ, some of the chemical compounds they contain bind to receptor molecules, and sensory messages are sent to the brain.

      The Jacobson's organ is useful in the process of communicating chemical messages, such as readiness for sexual activity (sex), between members of the same species. The organ also helps snakes hunt and track their prey. Much evidence suggests that this organ may also be involved in the detection of chemical signals related to aggression and territoriality. See also chemoreception.

George R. Zug
 

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Universalium. 2010.

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Look at other dictionaries:

  • Jacobson's organ — n vomeronasal organ …   Medical dictionary

  • Jacobson's organ — [jā′kəb sənz] n. either of a pair of olfactory sense organs in the roof of the mouth of many vertebrates, esp. snakes and lizards …   English World dictionary

  • Jacobson's organ — noun Etymology: Ludvig L. Jacobson died 1843 Danish anatomist Date: 1885 vomeronasal organ …   New Collegiate Dictionary

  • Jacobson's organ — noun Zoology a scent organ situated in the mouth of snakes, lizards, and some other vertebrates. Origin C19: named after the Dutch anatomist Ludwig L. Jacobson …   English new terms dictionary

  • Jacobson's organ — noun The vomeronasal organ, an auxiliary olfactory sense organ found in many animals …   Wiktionary

  • Jacobson's organ — Ja′cob•son s or′gan [[t]ˈdʒeɪ kəb sənz[/t]] n. anat. zool. either of a pair of olfactory pockets in the roof of the mouth, absent in primates but well developed in many vertebrates, esp. reptiles • Etymology: 1870–75; after L. L. Jacobson… …   From formal English to slang

  • jacobson's organ — noun Usage: usually capitalized J Etymology: after L.L.Jacobson : a slender horizontal canal in the nasal mucosa that ends in a blind pouch, has an olfactory function, and is rudimentary in adult man but highly developed in most reptiles …   Useful english dictionary

  • Jacobson — is a surname, and may also refer to:* Jacobson, Minnesota, USA * Jacobson v. United States , American legal case * Jacobson stores, American franchise * Vomeronasal organ, an auxiliary olfactory sense organ also called Jacobson s organ See also * …   Wikipedia

  • JACOBSON, LUDVIG LEVIN — (1783–1843), Danish physician, anatomist, and naturalist. He began his career as an assistant at the Academy of Surgery in Copenhagen and was a lecturer in chemistry at the Veterinary College. He began his studies in comparative anatomy and in… …   Encyclopedia of Judaism

  • organ of jacobson — Usage: usually capitalized J : jacobson s organ …   Useful english dictionary

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