Vomeronasal organ
Vomeronasal organ | |
---|---|
Details | |
Precursor | Nasal placode |
Lymph | Node |
Identifiers | |
Latin | organum vomeronasale |
MeSH | D019147 |
TA98 | A06.1.02.008 |
TA2 | 3141 |
FMA | 77280 |
Anatomical terminology |
The vomeronasal organ (VNO), or Jacobson's organ, is the paired auxiliary
The VNO contains the
VNO neurons are activated by the binding of certain chemicals to their
The VNO triggers the
Structure
The organ
The VNO is found at the base of the nasal cavity. It is split into two, being divided by the nasal septum, with both sides possessing an elongated C-shaped, or crescent, lumen. It is encompassed inside a bony or cartilaginous capsule which opens into the base of the nasal cavity.[8]
The system
The vomeronasal receptor neurons possess axons which travel from the VNO to the accessory olfactory bulb (AOB), which is also known as the vomeronasal bulb. These sensory receptors are located on the medial concave surface of the crescent lumen. The lateral, convex surface of the lumen is covered with non-sensory ciliated cells, where the basal cells are also found. At the dorsal and ventral aspect of the lumen are vomeronasal glands, which fill the vomeronasal lumen with fluid. Sitting next to the lumen are blood vessels that dilate or constrict, forming a vascular pump that deliver stimuli to the lumen. A thin duct, which opens onto the floor of the nasal cavity inside the nostril, is the only way of access for stimulus chemicals.
During embryological development, the vomeronasal sensory neurons form from the nasal (olfactory)
Sensory epithelium and receptors
The VNO is a tubular crescent shape and split into two pairs, separated by the
Three G-protein-coupled receptors have been identified in the VNO, each found in distinct regions: the V1Rs, V2Rs, and FPRs. V1Rs, V2Rs and FPRs are seven transmembrane receptors which are not closely related to odorant receptors expressed in the main olfactory neuroepithelium.[9]
- V1 receptors, V1Rs, are linked to the G protein, Gαi2. The benefit of the GPCR is that they signal in more than one direction. V1Rs are located on the apical compartment of the VNO and a relatively short NH2 terminal and have a great sequence diversity in their transmembrane domains. V1R is specifically expressed in the rodent vomeronasal organ (VNO) and is thought to be responsible for pheromone reception, eliciting a signal transduction.[10]
- V2 receptors, V2Rs, are linked to the G-protein, Gαo. These have long extracellular NH2 terminals which are thought to be the binding domain for pheromonal molecules and are located on the basal compartment of the VNO. V2R genes can be grouped into four separate families, labelled A – D. Family C V2Rs are quite distinct from the other families, and they are expressed in most basal neurons of the VNO.
The vomeronasal organ's sensory neurons act on a different signaling pathway than that of the main olfactory system's sensory neurons. Activation of the receptors stimulates phospholipase C,[11] which in turn opens the ion channel TRPC2.[12][13] Upon stimulation activated by pheromones, IP3 production has been shown to increase in VNO membranes in many animals, while adenylyl cyclase and cyclic adenosine monophosphate (cAMP), the major signaling transduction molecules of the main olfactory system, remain unaltered. This trend has been shown in many animals, such as the hamster, the pig, the rat, and the garter snake upon introduction of vaginal or seminal secretions into the environment.
V1Rs and V2Rs are activated by distinct ligands or pheromones.
- lipophilicodorants.
- Go proteins are activated by nonvolatile proteins, such as the major urinary proteins in mice[14][15] and exocrine gland-secreting peptide 1 (ESP1).[16]
Many vomeronasal neurons are activated by chemicals in urine. Some of the active compounds are sulfated
Recent studies proved a new family of formyl peptide receptor like proteins in VNO membranes of mice, which points to a close phylogenetic relation of signaling mechanisms used in olfaction and chemosensors.[5]
Sensory neurons
Vomeronasal sensory neurons are extremely sensitive and fire action potentials at currents as low as 1 pA. Many patch-clamp recordings have confirmed the sensitivity of the vomeronasal neurons. This sensitivity is tied to the fact that the resting potential of the vomeronasal neurons is relatively close to that of the firing threshold of these neurons. Vomeronasal sensory neurons also show remarkably slow adaptation and the firing rate increases with increasing current up to 10 pA. The main olfactory sensory neurons fire single burst action potentials and show a much quicker adaptation rate. Activating neurons that have V1 receptors, V1Rs, cause field potentials that have weak, fluctuating responses that are seen the anterior of the accessory olfactory bulb, AOB. Activation of neurons that contain V2 receptors, V2Rs, however, promote distinct oscillations in the posterior of the AOB.[18]
Function
In
In animals
The vomeronasal organ originated in
- Salamanders perform a nose-tapping behavior to presumably activate their VNO.[22]
- 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.[23]
- The organ is well developed in strepsirrhine primates such as lemurs and lorises,[24] developed to varying degrees in New World monkeys, and underdeveloped in Old World monkeys and apes.[25]
- prehensile structure, sometimes called a finger, at the tips of their trunks.[26][self-published source]
- Painted turtles use this organ to use their sense of smell underwater.[26]
- Garter snakes – In addition to the main olfactory system, olfaction. Vomodors are chemicals detected by the sensory cells from the vomeronasal organ through the process of vomerolfaction.[27] Upon entering the lumen of the organ, the chemical molecules will come into contact with the sensory cells which are attached to the neurosensory epithelium of the vomeronasal organ. More importantly, a new research has demonstrated that the vomeronasal organ is necessary in order for garter snake to respond to airborne prey odors, but fail to respond to airborne non-prey odors.[28]
In some other mammals the entire organ contracts or pumps in order to draw in the scents.[29]
Flehmen response
Some mammals, particularly
Flehmen behavior is associated with "anatomical specialization", and animals that present flehmen behavior have incisive papilla and ducts, which connect the oral cavity to the VNO, that are found behind their teeth. However, horses are the exception: they exhibit flehmen response but do not have an incisive duct communication between the nasal and the oral cavity because they do not breathe through their mouths; instead, the VNOs connect to the nasal passages by the nasopalatine duct.[30]
Cats use their vomeronasal organ when scent rubbing; they are able to discriminate between similar smelling substances using this organ, and then perform the rubbing behaviour.[31]
Evidence for existence in humans
Many studies have tried to determine whether there is a VNO in adult human beings. Trotier et al.
Given these findings, some scientists have argued that there is a VNO in adult human beings.
Among studies that use
History
The VNO was discovered by
References
- ^ Nakamuta S, Nakamuta N, Taniguchi K, Taniguchi K. Histological and ultrastructural characteristics of the primordial vomeronasal organ in lungfish. Anat Rec (Hoboken). 2012 Mar;295(3):481-91. doi: 10.1002/ar.22415. Epub 2012 Jan 23. PMID 22271496.
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- ^ S2CID 4302009.
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- ^ a b Jacobson, L. (1813). Anatomisk Beskrivelse over et nyt Organ i Huusdyrenes Næse. Veterinær=Selskapets Skrifter [in Danish] 2,209–246.
- ^ Meredith, Michael. "The Vomeronasal Organ". FSU Program in Neuroscience. Florida State University. Archived from the original on 2013-02-11. Retrieved 2013-05-27.
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- ^ "Aggression protein found in mice". BBC News. 5 December 2007. Retrieved 26 September 2009.
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- ^ "Kimball, J.W. Pheromones. Kimball's Biology Pages. Sep 2008". Archived from the original on 2018-01-21. Retrieved 2008-11-01.
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- ^ ]
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- ^ Briggs, Karen (2013-12-11). "Equine Sense of Smell". The Horse. Retrieved 2013-12-15.
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- ISBN 0-521-48526-6. p295
Further reading
- Døving KB, Trotier D (November 1998). "Structure and function of the vomeronasal organ". The Journal of Experimental Biology. 201 (Pt 21): 2913–2925. PMID 9866877.
- Silvotti L, Moiani A, Gatti R, Tirindelli R (December 2007). "Combinatorial co-expression of pheromone receptors, V2Rs". Journal of Neurochemistry. 103 (5): 1753–1763. S2CID 11198963.
- Keverne EB (October 1999). "The vomeronasal organ". Science. 286 (5440): 716–720. PMID 10531049.
- Meredith M (May 2001). "Human vomeronasal organ function: a critical review of best and worst cases". Chemical Senses. 26 (4): 433–445. S2CID 17248981.
- Evans CS (June 2006). "Accessory chemosignaling mechanisms in primates". American Journal of Primatology. 68 (6): 525–544. S2CID 25874777.
- Wekesa KS, Anholt RR (August 1997). "Pheromone regulated production of inositol-(1, 4, 5)-trisphosphate in the mammalian vomeronasal organ". Endocrinology. 138 (8): 3497–3504. PMID 9231804.
- Monti-Bloch L, Jennings-White C, Berliner DL (November 1998). "The human vomeronasal system. A review". Annals of the New York Academy of Sciences. 855 (1): 373–389. S2CID 38973467.