Vomeronasal Organ

In rodents, the nasal cavity contains two separate chemosensory epithelia, the main olfactory epithelium, located in the posterior dorsal aspect of the nasal cavity, and the vomeronasal/accessory olfactory epithelium, located in a capsule in the anterior aspect of the ventral floor of the nasal cavity. Both the main and accessory olfactory systems play a role in detection of biologically relevant odors. The accessory olfactory system has been implicated in response to pheromones, while the main olfactory system is thought to be a general molecular analyzer capable of detecting subtle differences in molecular structure of volatile odorants. However, the role of the two systems in detection of biologically relevant chemical signals appears to be partially overlapping. Thus, while it is clear that the accessory olfactory system is responsive to putative pheromones, the main olfactory system can also respond to some pheromones. Conversely, while the main olfactory system can mediate recognition of differences in genetic makeup by smell, the vomeronasal organ (VNO) also appears to participate in recognition of chemosensory differences between genetically distinct individuals. The most salient feature of our review of the literature is that there are no general rules that allow classification of the accessory olfactory system as a pheromone detector and the main olfactory system as a detector of general odorants. Instead, each behavior must be considered within a specific behavioral context to determine the role of these two chemosensory systems. In each case, one system or the other (or both) participates in a specific behavioral or hormonal response.

The effect of sensory input on hormones is essential to any explanation of mammalian behavior, including aspects of physical attraction. The chemical signals we send have direct and developmental effects on hormone levels in other people. Since we don t know either if, or how, visual cues might have direct and developmental effects on hormone levels in other people, the biological basis for the development of visually perceived human physical attraction is currently somewhat questionable. In contrast, the biological basis for the development of physical attraction based on chemical signals is well detailed.

Electrical stimulation of sympathetic fibres to the vomeronasal organ of the cat caused a suction of fluid into the lumen of the organ. A resting secretion was observed from the organ, and electrical stimulation of parasympathetic fibres caused secretion to drip from the vomeronasal duct. A model of a possible vasomotor pumping mechanism is discussed and the pathways taken by the autonomic fibres to the organ are described. Cat vomeronasal organ Autonomic innervation Stimulus access to vomeronasai organ Vomeronasal secretion Histology After sacrificing the animal the head was f'Lxed in 10% formal saline and whole sections of the nasal cavity were cut and observed under a x 10 binocular microscope. Some

The effect of sensory input on hormones is essential to any explanation of mammalian behavior, including aspects of physical attraction. The chemical signals we send have direct and developmental effects on hormone levels in other people. Since we don't know either if, or how, visual cues might have direct and developmental effects on hormone levels in other people, the biological basis for the development of visually perceived human physical attraction is currently somewhat questionable. In contrast, the biological basis for the development of physical attraction based on chemical signals is well detailed.

The literature describing the formation of the incisive canal is very bizarre. The fusion of the primary and secondary palatal processes leads to formation of a triangular seam, which erroneously has been taken for the future incisive canal. If so, the nasopalatine (incisive) nerve and its accompanying vessels were to run through the primary oronasal cavity, which is not compatible with our biological experience. This study was undertaken to shed light on this region of fusion. We focus on the formation of the incisive canal; the neighboring nasopalatine ducts, which are a transient formation, are mentioned where present. A series of seven horizontal cross-sections of human embryos and fetuses from the 7th to the 24th week of pregnancy (between 25 and 225 mm CRL, crownrump-length) were examined histologically and partly reconstructed in 3D applying the software analySIS (Soft Imaging Systems, Münster, Germany). The incisive canal did not develop at the junction of the primary and the secondary palate, but within the primary palate rostral to that location. The nasopalatine nerve and the nasopalatine artery are structures that exist before ossification starts in the area of the future incisive canal. The neighboring nasopalatine ducts were found in regions laterally and anterolaterally of the nasopalatine nerve, and it was mostly separated from it by bone. In advanced stages of development, the nasopalatine duct only existed as single epithelial remnants and was prone to obliteration.

The role of pheromones in orchestrating social behaviors in reptiles is reviewed. Although all reptile orders are examined, the vast majority of the literature has dealt only with squamates, primarily snakes and lizards. The literature is surprisingly large, but most studies have explored relatively few behaviors. The evolution of chemical signaling in reptiles is discussed along with behaviors governed by pheromones including conspecific trailing, male-male agonistic interactions, sex recognition and sex pheromones, and reptilian predator recognition. Nonreptilian prey recognition by chemical cues was not reviewed. The recent literature has focused on two model systems where extensive chemical ecology studies have been conducted: the reproductive ecology of garter snakes and the behavioral ecology of Iberian lacertid lizards. In these two systems, enough is known about the chemical constituents that mediate behaviors to explore the evolution of chemical signaling mechanisms that affect life history patterns. In addition, these models illuminate natural and sexual selection processes which have lead to complex chemical signals whose different components and concentrations provide essential information about individuals to conspecifics. Reptiles provide excellent candidates for further studies in this regard not only in squamates, but also in the orders where little experimental work has been conducted to date.

The buller steer syndrome is found among confined and pasture-kept cattle. The buller behavior occurs when a steer is repeatedly mounted (“buller”) and ridden by its pen mates (“rider”) until it is injured or killed. The usual practice is to remove the animal being ridden. The ridden animals are typically grouped together in a “buller” pen where little or no

Tongue-flicking is a sensory-gathering behavior used by snakes to deliver odorants to the vomeronasal organ. In the present study we provide a detailed description of environmental control and motor patterns of tongue-flicking in garter snakes, Thamnophis sirtalis. Tongue-flicks were monitored during prey extract trailing, foraging, delivery of air-borne odors and in an open field. Tongue-flick rates increased during airborne odor delivery and as a function of prey extract concentration during trailing, as previously reported. Motivation and prey consumption appeared to modify tongue-flick patterns since 1. tongue-flick rates were higher under foraging conditions than in an open field where no prior prey consumption had occurred and no prey odors were present; and 2. tongue-flick rates were elevated after prey consumption. The number of oscillations and the duration of tongue extensions were significantly reduced following tongue-substrate touches, suggesting that tongue contact with the substrate is the immediate stimulus for tongue retraction.

Even in rodents, there is no clear evidence of the existence of sexual pheromones mediating instinctive intersexual attraction. In this review we discuss previous results of our group indicating that female mice reared in the absence of male-derived chemosignals are ‘attracted’ by some components of male-soiled bedding, presumably detected by the vomeronasal organ. In contrast, male odors (olfactory stimuli) only acquire attractiveness by means of their association with the innately ‘attractive’ vomeronasal-detected pheromones. These ‘attractive’ male pheromones are rewarding to adult females, since they induce conditioned preference for a place where they are repeatedly presented to the females. Pheromone reward seems independent of the dopaminergic neurotransmission in the tegmento-striatal pathway, and uses mechanisms and circuits apparently different to those of other natural reinforcers.

The vomeronasal organ (VNO), also known as the Jacobson's organ, is a bilateral chemosensory organ found at the base of the nasal cavity specialized for the detection of higher-molecular weight (non-volatile) chemostimuli. It has been linked to pheromone detection. The VNO has been well studied in nocturnal lemurs and lorises, but poorly studied in diurnal/cathemeral species despite the large repertoire of olfactory behaviors noted in species such as Lemur catta. Here, the VNO and associated structures were studied microanatomically in one adult female and one adult male L. catta. Traditional and immunohistochemical procedures demonstrate the VNO epithelium consists of multiple rows of sensory neurons. Immunoreactivity to Growth-associated protein 43 (GAP43) indicates the VNO is postnatally neurogenic. In volume, the VNO neuroepithelium scales similarly to palatal length compared to nocturnal strepsirrhines. Numerous taste buds present at the oral opening to the nasopalatine duc...

Mammals rely heavily on olfaction to interact adequately with each other and with their environment 1 . They make use of seventransmembrane G-protein-coupled receptors to identify odorants and pheromones. These receptors are present on dendrites of olfactory sensory neurons located in the main olfactory or vomeronasal sensory epithelia, and pertain to the odorant 2 , trace amineassociated receptor 3 and vomeronasal type 1 (ref. 4) or 2 (refs 5-7) receptor superfamilies. Whether these four sensor classes represent the complete olfactory molecular repertoire used by mammals to make sense of the outside world is unknown. Here we report the expression of formyl peptide receptor-related genes by vomeronasal sensory neurons, in multiple mammalian species. Similar to the four known olfactory receptor gene classes, these genes encode seven-transmembrane proteins, and are characterized by monogenic transcription and a punctate expression pattern in the sensory neuroepithelium. In vitro expression of mouse formyl peptide receptor-like 1, 3, 4, 6 and 7 provides sensitivity to disease/inflammation-related ligands. Establishing an in situ approach that combines whole-mount vomeronasal preparations with dendritic calcium imaging in the intact neuroepithelium, we show neuronal responses to the same molecules, which therefore represent a new class of vomeronasal agonists. Taken together, these results suggest that formyl peptide receptor-like proteins have an olfactory function associated with the identification of pathogens, or of pathogenic states.

Vomeronasal receptor genes have frequently been invoked as integral to the establishment and maintenance of species boundaries among mammals due to the elaborate one-to-one correspondence between semiochemical signals and neuronal sensory inputs. Here, we report the most extensive sample of vomeronasal receptor class 1 (V1R) sequences ever generated for a diverse yet phylogenetically coherent group of mammals, the tooth-combed primates (suborder Strepsirrhini). Phylogenetic analysis confirms our intensive sampling from a single V1R subfamily, apparently unique to the strepsirrhine primates. We designate this subfamily as V1Rstrep. The subfamily retains extensive repertoires of gene copies that descend from an ancestral gene duplication that appears to have occurred prior to the diversification of all lemuriform primates excluding the basal genus Daubentonia (the aye-aye). We refer to the descendent clades as V1Rstrep-α and V1Rstrep-β. Comparison of the two clades reveals different amino acid compositions corresponding to the predicted ligand-binding site and thus potentially to altered functional profiles between the two. In agreement with previous studies of the mouse lemur (genus, Microcebus), the majority of V1Rstrep gene copies appear to be intact and under strong positive selection, particularly within transmembrane regions. Finally, despite the surprisingly high number of gene copies identified in this study, it is nonetheless probable that V1R diversity remains underestimated in these non-model primates and that complete characterization will be limited until high-coverage assembled genomes are available.

Because information about gender, kin, and social status are essential for reproduction and survival, it seems likely that specialized neural mechanisms have evolved to process social information. This review describes recent studies of four aspects of social information processing: (a) perception of social signals via the vomeronasal system, (b) formation of social memory via long-term filial imprinting and short-term recognition, (c) motivation for parental behavior and pair bonding, and (d) the neural consequences of social experience. Results from these studies and some recent functional imaging studies in human subjects begin to define the circuitry of a "social brain." Such neurodevelopmental disorders as autism and schizophrenia are characterized by abnormal social cognition and corresponding deficits in social behavior; thus social neuroscience offers an important opportunity for translational research with an impact on public health.

Some chemicals elicit innate emotionally laden behavioral responses. Pheromones mediate sexual attraction, parental care or agonistic confrontation, whereas predators' kairomones elicit defensive behaviors in their preys. This essay explores the hypothesis that the detection of these semiochemicals relies on highly specific olfactory and/or vomeronasal receptors. The V1R, V2R, and formyl-peptide vomeronasal receptors bind their ligands in highly specific and sensitive way, thus being good candidates for pheromoneor kairomone-detectors (e.g., secreted and excreted proteins, peptides and lipophilic volatiles). The olfactory epithelium also expresses specific receptors, for example trace amine-associated receptors (TAAR) and guanylyl cyclase receptors (GC-D and other types), some of which bind kairomones and putative pheromones. However, most of the olfactory neurons express canonical olfactory receptors (ORs) that bind many ligands with different affinity, being not suitable for mediating responses to pheromones and kairomones. In this respect, trimethylthiazoline (TMT) is considered a fox-derived kairomone for mice and rats, but it seems to be detected by canonical ORs. Therefore, we have reassessed the kairomonal nature of TMT by analyzing the behavioral responses of outbred (CD1) and inbred mice (C57BL/J6) to TMT. Our results confirm that both mouse strains avoid TMT, which increases immobility in C57BL/J6, but not CD1 mice. However, mice of both strains sniff at TMT throughout the test and show no trace of TMT-induced contextual conditioning (immobility or avoidance). This suggests that TMT is not a kairomone but, similar to a loud noise, in high concentrations it induces aversion and stress as unspecific responses to a strong olfactory stimulation.

Because humans seem to lack neuronal elements in the vomeronasal organ (VNO), many scientists believe that humans are unable to detect pheromones. This view is challenged by the observations that pheromone-like compounds, 4,16-androstadien-3-one (AND) and oestra-1,3,5(10),16-tetraen-3-ol (EST), activate the human hypothalamus. Whether these activations are mediated via VNO, venous blood or olfactory mucosa is presently unknown. To disentangle between the three alternatives, we conducted activation studies in 12 heterosexual males with chronic anosmia because of nasal polyps. Polyposis hampers signal transduction via the olfactory mucosa without interfering with the VNO or the pheromone transport via venous blood. Twelve healthy men served as controls. Subjects were investigated with 15 OÀ ÀH 2 O PET during smelling of odorless air (base line), AND, EST, vanillin, and acetone. Smelling of EST activated the anterior hypothalamus in controls, but not anosmics. Neither did the anosmics display cerebral activations with AND or vanillin. Clusters were detected only with the trigeminal odorant acetone, and only in the thalamus, brainstem, the anterior cingulate, and parts of the sensorimotor cortex. Direct comparisons with controls (controls-anosmics) showed clusters in the olfactory cortex (amygdala and piriform cortex) with AND, vanillin, and acetone, and in the anterior hypothalamus with EST. The observed absence of olfactory and presence of trigeminal activations in anosmics indicates that polyposis primarily affected signal processing via the olfactory mucosa. The anosmics inability to activate the hypothalamus with EST, therefore, suggests that in healthy men EST signals were primarily transmitted via the olfactory system. Hum Brain Mapp 30: [3057][3058][3059][3060][3061][3062][3063][3064][3065] 2009. V V C 2009 Wiley-Liss, Inc.

Mammalian social systems rely on signals passed between individuals conveying information including sex, reproductive status, individual identity, ownership, competitive ability and health status. Many of these signals take the form of complex mixtures of molecules sensed by chemosensory systems and have important influences on a variety of behaviours that are vital for reproductive success, such as parent-offspring attachment, mate choice and territorial marking. This article aims to review the nature of these chemosensory cues and the neural pathways mediating their physiological and behavioural effects. Despite the complexities of mammalian societies, there are instances where single molecules can act as classical pheromones attracting interest and approach behaviour. Chemosignals with relatively high volatility can be used to signal at a distance and are sensed by the main olfactory system. Most mammals also possess a vomeronasal system, which is specialized to detect relatively non-volatile chemosensory cues following direct contact. Single attractant molecules are sensed by highly specific receptors using a labelled line pathway. These act alongside more complex mixtures of signals that are required to signal individual identity. There are multiple sources of such individuality chemosignals, based on the highly polymorphic genes of the major histocompatibility complex (MHC) or lipocalins such as the mouse major urinary proteins. The individual profile of volatile components that make up an individual odour signature can be sensed by the main olfactory system, as the pattern of activity across an array of broadly tuned receptor types. In addition, the vomeronasal system can respond highly selectively to non-volatile peptide ligands associated with the MHC, acting at the V2r class of vomeronasal receptor.

Molecular approaches and genetic manipulations have provided novel insights into the processing of pheromone-mediated information by the olfactory and vomeronasal systems of mammals. We will review and discuss the specific contribution of each of the two chemosensory systems that ensure specific behavioral responses to conspecific animals.

The present study on the main olfactory system (MOS) and the accessory olfactory system (AOS) documents the functional morphology of the rodent olfactory region and that of the vomeronasal organ (VNO) using light and electron microscopical techniques. Special attention is given to the cytoarchitecture of the sensory epithelia, i. e. the olfactory epithelium (OE) of the regio olfactoria and the neuroepithelium of the VNO (VNO-NE).

Cet article analyse les controverses scientifiques concernant le rôle des phéromones dans les attirances sexuelles chez l’être humain mais aussi la synchronisation des cycles menstruels chez les femmes. Il détaille les quatre points sur lesquels l’implication des phéromones dans les comportements sexuels humains fait l’objet aussi bien d’affirmations présentées comme des découvertes ou des données acquises, que d’interrogations voire de remises en question : si les phéromones sont des odeurs ou des substances chimiques distinctes, si l’être humain dispose d’un organe fonctionnel idoine à leur détection ou si elles sont captées par le système olfactif principal au même titre que les odeurs, si l’absence de réponse comportementale stéréotypée chez l’être humain permet de maintenir ou non l’hypothèse d’un rôle significatif ou amoindri des phéromones, et enfin, si l’être humain émet ou non des phéromones. L’analyse des publications sur les rôles supposés des phéromones dans l’espèce humaine permet tout autant de mettre en évidence les difficultés méthodologiques dans les expériences menées et les mesures statistiques effectuées, que les variations conceptuelles auxquelles est soumis le vocable de « phéromone ». En regard de la définition des phéromones proposée par Karlson et Lüscher à l’aube des années 1960, la désignation d’hormones stéroïdiennes telles l’androstadiénone ou l’estratetraenol comme des phéromones ne fait pas l’unanimité, alors qu’elle paraît évidente pour un certain nombre de chercheuses et de chercheurs. Apparaît également la diversité des champs scientifiques des chercheurs étudiant les phéromones : biologistes, biochimistes, neuroscientifiques, oto-rhino-laryngologues, zoologues, anthropologues, psychologues… Les enjeux de ces controverses sont multiples : d’une part, elles soulèvent la question des procédés méthodologiques mis en œuvre et des conclusions qu’il est possible de tirer des résultats obtenus ; d’autre part, elles alimentent les débats récurrents sur la part de déterminismes biologiques dans les comportements humains dont les chercheurs en sciences humaines et sociales rendent compte à partir de déterminants sociaux. Cette étude de controverse ne permet pas in fine de considérer comme acquis un quelconque rôle phéromonal dans les comportements sexuels humains.

English version :
This article investigates the ongoing scientific wrangling concerning the role of pheromones in sexual attraction in human beings, and also in the synchronisation of menstrual cycles in females. It looks in detail at the four areas where the involvement of pheromones in sexual behaviour in humans has given rise to affirmations presented as discoveries or acquired data, and at the same time to questions or even challenges: whether pheromones are distinct smells or chemical substances, whether the human being has an appropriate functional organ for detecting them or if they are detected by the main olfactory system in the same way as smells, whether the absence of stereotypical behavioural response in the human being allows the hypothesis of a significant role to be confirmed or disregarded, and finally, whether the human being releases pheromones or not. A review of literature on the hypothetical role of pheromones in humans evidences some methodological difficulties in the experiments conducted and the statistical measurements made, and as many variations in what is understood by the very concept of the word “pheromone”. Looking at the definition of pheromones coined by Karlson and Lüscher at the beginning of the 1960s, steroid hormones such as androstadienone or estratetraenol are considered to be pheromones, and although not everyone agrees with this definition, for other researchers it is undeniable. There are also differences in the scientific specialities of researchers studying pheromones: biologists, biochemists, neuroscientists, ENT specialists, zoologists, anthropologists, psychologists, etc. The stakes of the controversies are high: they raise the question of the methodologies used in the studies and the reliability of their conclusions; they also fuel the regular discussions about the share of biological determinism in human behaviour that researchers in human and social sciences measure based on social determinants. Ultimately, this study of controversy shows that a possible role for pheromones in human sexual behaviour is not something that can by any means be taken for granted.

In tetrapods, the medial amygdala is a forebrain center that integrates olfactory and/or vomeronasal signals with the endocrine and autonomic systems, playing a key role in different social behaviors. The vomeronasal system has undergone important changes during evolution, which may be behind some interspecies differences in chemosensorymediated social behavior. These evolutionary changes are associated with variations in vomeronasal-recipient brain structures, including the medial amygdala. Herein, we employed an evolutionary developmental biology approach for trying to understand the function and evolution of the medial amygdala. For that purpose, we reviewed published data on fate mapping in mouse, and the expression of orthologous developmental regulatory genes (Nkx2.1, Lhx6, Shh, Tbr1, Lhx9, Lhx5, Otp, and Pax6) in embryos of mouse, chicken, emydid turtles, and a pipid frog. We also analyzed novel data on Lhx9 and Otp in a lacertid lizard. Based on distinct Abbreviations used: AAv 5 anterior amygdala, ventral part; ACo 5 anterior cortical amygdalar area; AHN 5 anterior hypothalamic nucleus; AOB 5 accessory olfactory bulb; AON 5 anterior olfactory nucleus; APH 5 parahippocampal area (chicken); Arc 5 arcopallium (part of the pallial amygdala in chicken); AStr 5 amygdalo-striatal transition area; BAOT 5 bed nucleus of the accessory olfactory bulb; Bas 5 basal nucleus (Meynert); BC 5 basal amygdalar complex; BL 5 basolateral amygdalar nucleus; BLA 5 basolateral amygdalar nucleus, anterior part; BLV 5 basolateral amygdalar nucleus, ventral part; BM 5 basomedial amygdalar nucleus; BMA 5 basomedial amygdalar nucleus, anterior part; BSTia 5 bed nucleus of the stria terminalis, intraamygdaloid part; BSTM 5 bed nucleus of the stria terminalis, medial part; BSTM1 5 dorsolateral subnucleus of BSTM (chicken); BSTM2 5 ventromedial subnucleus of BSTM (chicken); CDL 5 dorsolateral corticoid area (chicken); Ce 5 central amygdala (central amygdalar nucleus); Co 5 cortical amygdalar area (chicken, comparable to ACo of mammals); CPu 5 caudate-putamen; CxA 5 cortico-amygdalar transition area; DC 5 dorsal cortex (reptile); DEn 5 dorsal endopiriform nucleus; EMT 5 prethalamic (or thalamic) eminence; Ent 5 entorhinal cortex; Gaba1 5 g-aminobutyric acid (GABA)-ergic cells; Glu1 5 glutamatergic cells; GP 5 globus pallidus; GPL 5 globus pallidus, lateral part; GPM 5 globus pallidus, medial part; Hb 5 basal hypothalamus; Hip 5 hippocampal formation, rostral olfacto-recipient part; I 5 intercalated cell groups of the amygdale; ic 5 internal capsule; IM 5 intercalated cell groups of the amygdala, main division; L 5 lateral amygdalar nucleus; LC 5 lateral cortex (reptile); LGE 5 lateral ganglionic eminence; LOT 5 nucleus of the lateral olfactory tract; LOT1 5 nucleus of the lateral olfactory tract, layer 1; MC 5 medial cortex (reptile); Me 5 medial amygdala in nonmammals; MeA 5 medial amygdala, anterior part; MeAV 5 medial amygdala, anteroventral part; MePD 5 medial amygdala, posterodorsal part; MePV 5 medial amygdala, posteroventral part; MePVc 5 medial amygdala, posteroventral part, central subdivision; MePVs 5 medial amygdala, posteroventral part, superficial subdivision; MGEd 5 medial ganglionic eminence, dorsal part; MGEcvmedial ganglionic eminence, caudoventral part (previously named or included as part of the anterior peduncular area or AEP); MOB 5 main olfactory bulb; MPN 5 medial preoptic nucleus; MS 5 medial septum; NC 5 nidopallium caudale or caudal nidopallium (chicken); NCL 5 caudolateral nidopallium (chicken); NCx 5 neocortex; NSph 5 nucleus sphericus (reptile, it appears comparable to PMCo of mammals); ot 5 optic tract; PDVR 5 posterior dorsal ventricular ridge (reptile); Pe 5 periventricular hypothalamic nucleus; Pir 5 piriform cortex; PLCo 5 posterolateral cortical amygdalar area; PMCo 5 posteromedial cortical amygdalar area; PMv 5 ventral premammillary nucleus; POC 5 commissural preoptic area (or commissural septo-preoptic area); POH 5 preopto-hypothalamic boundary; PTh 5 prethalamus; PVN 5 paraventricular hypothalamic nucleus; PVT 5 paraventricular thalamic nucleus; S 5 subpallium; Se 5 septum; sm 5 stria medullaris; SO 5 supraoptic nucleus; SPV 5 supraopto-paraventricular hypothalamic domain; svz 5 subventricular zone; Th 5 thalamus; Tu 5 ofactory tuberculum; VAA 5 ventral anterior amygdala (reptile, comparable to avian Co and mammalian ACo); ve 5 ventricle; VMHdm 5 ventromedial hypothalamic nucleus, dorsomedial part; VMHvl 5 ventromedial hypothalamic nucleus, ventrolateral part; VP 5 ventral pallium; vz 5 ventricular zone

The vomeronasal organ (VNO) constitutes an accessory olfactory organ that receives chemical stimuli, pheromones, which elicit behavioral, reproductive, or neuroendocrine responses among individuals of the same species. In many macrosmatic animals, the morphological substrate constitutes a separate organ system consisting of a vomeronasal duct (ductus vomeronasalis, VND), equipped with chemosensory cells, and a vomeronasal nerve (nervus vomeronasalis, VNN) conducting information into the accessory olfactory bulb (AOB) in the central nervous system (CNS). Recent data require that the long-accepted dual functionality of a main olfactory system and the VNO be reexamined, since all species without a VNO are nevertheless sexually active, and species possessing a VNO also can sense other than "vomeronasal" stimuli via the vomeronasal epithelium (VNE). The human case constitutes a borderline situation, as its embryonic VNO anlage exerts a developmental track common to most macrosm...

Introduction: Most mammalians possess an accessory olfactory system, which its first part is called vomeronasal organ (VNO). In this research, we studied the structure of this organ in Azerbaijani red fox. Methods: Heads of 10 healthy male fox carcasses were collected from areas around Tabriz and transferred to the laboratory in frozen form or in fixative solution. Biometrical experiments were done, then the maxillary bones cut into 5 pieces, and the pieces decalcified and embedded in paraffin. Then, 7-µm tissue sections were stained with H&E, PAS, and Masson's trichrome methods and explored under light microscope. Results: Two ducts of VNO start at the roof of mouth, about 3.17±0.28 mm behind the central incisor teeth, extend back into 2 sides of nasal septum and end near the first or second premolar teeth. This organ is surrounded by a hyaline cartilage, which is C-shaped in the first pieces and transform to "J" shape structure toward the back. The lining epithelium of lumen changes from nonkeratinized stratified squamous epithelium near the valve to pseudostratified columnar in the posterior portions. Presence of bipolar neurons in epithelium of medial wall shows VNO sensory function of smelling. Lamina propria-tunica submucosa in most portions have many serous and mucous secretory units and composed of a loose connective tissue with numerous blood vessels, which secretes pheromone. Also, this is an erectile tissue that can function in association with flehmen reaction to push toward the sensory epithelium of VNO. Conclusion: Orifice of VNO of Azerbaijani red fox same more mammalian open in oral cavity. It has 2 type epithelial tissues in end region. Sensory epithelium indicates important role of this organ for received of Pheromones.

The effect of sensory input on hormones is essential to any explanation of mammalian behavior, including aspects of physical attraction. The chemical signals we send have direct and developmental effects on hormone levels in other people. Since we don t know either if, or how, visual cues might have direct and developmental effects on hormone levels in other people, the biological basis for the development of visually perceived human physical attraction is currently somewhat questionable. In contrast, the biological basis for the development of physical attraction based on chemical signals is well detailed.

Nearly all vertebrates possess an olfactory organ but the vomeronasal organ is a synapomorphy for tetrapods. Nevertheless, it has been lost in several groups of tetrapods, including aquatic and marine animals. The present study examines the development of the olfactory and vomeronasal organs in two terrestrial anurans that exhibit different developmental modes. This study compares the development of the olfactory and vomeronasal organs in metamorphic anurans that exhibit an aquatic larva (Bufo americanus) and directly developing anurans that have eliminated the tadpole (Eleutherodactylus coqui). The olfactory epithelium in larval B. americanus is divided into dorsal and ventral branches in the rostral and mid-nasal regions. The larval olfactory pattern in E. coqui has been eliminated. Ontogeny of the olfactory system in E. coqui embryos starts to vary substantially from the larval pattern around the time of operculum development, the temporal period when the larval stage is hypothesized to have been eliminated. The nasal anatomy of the two frogs does not appear morphologically similar until the late stages of embryogenesis in E. coqui and the terminal portion of metamorphosis in B. americanus. Both species and their respective developing offspring, aquatic tadpoles and terrestrial egg/embryos, possess a vomeronasal organ. The vomeronasal organ develops at mid-embryogenesis in E. coqui and during the middle of the larval period in B. americanus, which is relatively late for neobatrachians. Development of the vomeronasal organ in both frogs is linked to the developmental pattern of the olfactory system. This study supports the hypothesis that the most recent common ancestor of tetrapods possessed a vomeronasal organ and was aquatic, and that the vomeronasal organ was retained in the Amphibia, but lost in some other groups of tetrapods, including aquatic and marine animals.

Physiology and pathology have a big deal on tissue morphology, and the intrinsic spatial resolution of an atomic force microscope (AFM) is able to observe ultrastructural details. In order to investigate cellular and subcellular structures in histological sections with the AFM, we used a new simple method for sample preparation, i.e. chemical etching of semithin sections from epoxy resin-embedded specimens:

Squamate reptiles (snakes, lizards, amphisbaenians) rely heavily on chemosensory cues to identify, locate and choose between suitable prey items, but comparatively little research has focused on the chemical ecology of threatened squamate species. Such knowledge highlights ecologically important aspects of their survival. Due to gape limitations, squamates often demonstrate ontogenetic shifts in their diet where they consume larger prey as they grow older and their gape size increases. This shift enables squamates—especially snakes—to exploit new resources in their environments, usually mammalian prey. To test for ontogenetic variation in prey odor responses of a threatened snake species, the Northern pine snake (Pituophis melanoleucus melanoleucus), we presented food-naïve neonates and food-experienced adults with potential prey and non-prey animal scents and quantified their behavioral responses. Our data indicate a strong response to rodent scents from both neonates and adults. Further, neonates showed more frequent investigative probing and retreating behaviors from scented swabs and a higher rate of tongue-flicking than adults. We also developed a new metric for measuring snake responses to prey odor, a tongue-flick reaction score (TFRS), that incorporates investigative behaviors that may be unique to constrictor-type snakes. The TFRS did not differ between age classes and was highest when rodent odors were tested. A canonical discriminant analysis confirmed the relationship between TFRS behavioral components and tested chemical signal reactions. Based on our data, P. melanoleucus may fall into a category of snakes that exhibit an ontogenetic telescope rather than a general ontogenetic shift in their prey odor responses.

In order to gain insight into sensory processing modulating reproductive behavioral and endocrine changes, we have aimed at identifying afferent pathways to neurons synthesizing luteinizing hormone-releasing hormone (LHRH, also known as gonadotropin-releasing hormone [GnRH]), a key neurohormone of reproduction. Injection of conditional pseudorabies virus into the brain of an LHRH::CRE mouse line led to the identification of neuronal networks connected to LHRH neurons. Remarkably, and in contrast to established notions on the nature of LHRH neuronal inputs, our data identify major olfactory projection pathways originating from a discrete population of olfactory sensory neurons but fail to document any synaptic connectivity with the vomeronasal system. Accordingly, chemosensory modulation of LHRH neuronal activity and mating behavior are dramatically impaired in absence of olfactory function, while they appear unaffected in mouse mutants lacking vomeronasal signaling. Further visualization of afferents to LHRH neurons across the brain offers a unique opportunity to uncover complex polysynaptic circuits modulating reproduction and fertility. ful discussions and comments on the manuscript, P. Choi and C. Chen for RNA probes, Drs. T. Kimhi, A. Lanjuin, and S. Santoro for help with experiments, M. Eldridge for producing and testing the virus stocks, and Dr. B. Roska for useful advice.

The vomeronasal system of mice is thought to be specialized in the detection of pheromones. Two multigene families have been identified that encode proteins with seven putative transmembrane domains and that are expressed selectively in subsets of neurons of the vomeronasal organ. The products of these vomeronasal receptor (Vr) genes are regarded as candidate pheromone receptors. Little is known about their genomic organization and sequence diversity, and only five sequences of mouse V1r coding regions are publicly available. Here, we have begun to characterize systematically the V1r repertoire in the mouse. We isolated 107 bacterial artificial chromosomes (BACs) containing V1r genes from a 129 mouse library. Hybridization experiments indicate that at least 107 V1r-like sequences reside on these BACs. We assembled most of the BACs into six contigs, of which one major contig and one minor contig were characterized in detail. The major contig is 630-860 kb long, encompasses a cluster of 21-48 V1r genes, and contains marker D6Mit227. Sequencing of the coding regions was facilitated by the absence of introns. We determined the sequence of the coding region of 25 possibly functional V1r genes and seven pseudogenes. The functional V1rs can be arranged into three groups; V1rs of one group are novel and substantially divergent from the other V1rs. The genomic and sequence information described here should be useful in defining the biological function of these receptors.

The connections of the olfactory bulbs of Podarcis hispanica were studied by tract-tracing of injected horseradish peroxidase. Restricted injections into the main olfactory bulb (MOB) resulted in bilateral terminallike labeling in the medial part of the anterior olfactory nucleus (AON) and in the rostral septum, lateral cortex, nucleus of the lateral olfactory tract, and ventrolateral amygdaloid nucleus. Bilateral retrograde labeling was found in the rostral lateral cortex and in the medial and dorsolateral AON. Ipsilaterally the dorsal cortex, nucleus of the diagonal band, lateral preoptic area, and dorsolateral amygdala showed labeled cell bodies. Retrogradely labeled cells were also found in the midbrain raphe nucleus.Results from injections into the rostral lateral cortex and lateral olfactory tract indicate that the mitral cells are the origin of the centripetal projections of the MOB.Injections in the accessory olfactory bulb (AOB) produced ipsilateral terminallike labeling of the ventral AON, bed nucleus of the accessory olfactory tract, central and ventromedial amygdaloid nuclei, medial part of the bed nucleus of the stria terminalis, and nucleus sphericus. Retrograde labeling of neurons was observed ipsilaterally in the bed nucleus of the accessory olfactory tract and stria terminalis, in the central amygdaloid nucleus, dorsal cortex, and nucleus of the diagonal band. Bilateral labeling of somata was found in the ventral AON, the nucleus sphericus (hilus), and in the mesencephalic raphe nucleus and locus coeruleus.Injections into the dorsal amygdala showed that the mitral neurons are the cells of origin of the AOB centripetal projections. Reciprocal connections are present between AOB and MOB.To our knowledge, this is the first study to address the afferent connections of the olfactory bulbs in a reptile. On the basis of the available data, a discussion is provided of the similarities and differences between the reptilian and mammalian olfactory systems, as well as of the possible functional role of the main olfactory connections in reptiles.

Apically and basally located receptor neurons in the vomeronasal sensory epithelium express Gi2α- and Goα-proteins, V1R and V2R vomeronasal receptors, project to the anterior and posterior accessory olfactory bulb and respond to different stimuli, respectively. The extent to which secondary projections from the two portions of the accessory olfactory bulb are convergent in the vomeronasal amygdala is controversial. This issue is addressed by using anterograde and retrograde tract-tracing methods in rats including electron microscopy. Injections of dextran-amines, Fluoro Gold, cholera toxin-B subunit and Fast Blue were delivered to the anterior and posterior accessory olfactory bulb, bed nucleus of the stria terminalis, dorsal anterior amygdala and bed nucleus of the accessory olfactory tract/anteroventral medial amygdaloid nucleus. We have demonstrated that, apart from common vomeronasal-recipient areas, only the anterior accessory olfactory bulb projects to the bed nucleus of the stria terminalis, medial division, posteromedial part, and only the posterior accessory olfactory bulb projects to the dorsal anterior amygdala and deep cell layers of the bed nucleus of the accessory olfactory tract and the anteroventral medial amygdaloid nucleus. These results provide evidence that, excluding areas of convergence, the V1R and V2R vomeronasal pathways project to specific areas of the amygdala. These two vomeronasal subsystems are therefore anatomically and functionally separated in the telencephalon.

The present study on the main olfactory system (MOS) and the accessory olfactory system (AOS) documents the functional morphology of the rodent olfactory region and that of the vomeronasal organ (VNO) using light and electron microscopical techniques. Special attention is given to the cytoarchitecture of the sensory epithelia, i. e. the olfactory epithelium (OE) of the regio olfactoria and the neuroepithelium of the VNO (VNO-NE).

In rodents, sexual advertisement and gender recognition are mostly (if not exclusively) mediated by chemosignals. Specifically, there is ample evidence indicating that female mice are 'innately' attracted by male sexual pheromones that have critical non-volatile components and are detected by the vomeronasal organ. These pheromones can only get access to the vomeronasal organ by active pumping mechanisms that require close contact with the source of the stimulus (e.g. urine marks) during chemoinvestigation.

Social behaviors of most mammals are affected by chemical signals, pheromones, exchanged between conspecifics. Previous experiments have shown that behavioral responses to the same pheromone differ depending on the sex and endocrine status of the respondent. Although the exact mechanism of this dimorphism is not known, one possible contributor may be due to sexually dimorphic receptors or due to differences in central processing within the brain. In order to investigate the differences in response between male and female mice to the same pheromonal stimulus two urinary compounds (2-heptanone and 2,5dimethylpyrazine) were used to stimulate the production of Inositol (1,4,5)-trisphosphate (IP 3) in microvillar membrane preparations of the vomeronasal organ as an indirect measurement of pheromonal stimulation. Incubation of such membranes from prepubertal mice with urine from the same sex or opposite sex, results in an increase in production of IP 3. This stimulation is mimicked by GTPγS and blocked by GDPβS. Furthermore we found that 2-heptanone present in both male and female urine was capable of stimulating increased production of IP 3 in the female VNO but not the male VNO. Finally, 2,5-dimethylpyrazine present only in female urine was also only capable of stimulating increased production of IP 3 in the female VNO.

A male-specific major urinary protein named darcin is attractive to female mice, stimulates a 19 learned attraction to volatile components of a male's urinary odour (Roberts et al., 2010, 20 BMC Biol 8:75) and induces spatial learning , Science 338:1462. In 21 the present work we show that darcin also induces a learned attraction for a previously 22 neutral olfactory stimulus (the odorant isoamyl acetate). However, the attractive properties of 23 darcin may change as a function of female physiological state. For example, during the 24 period of lactation female mice display aggressive behaviour against intruders, which is 25 enhanced when confronted with adult males. Therefore, the endocrinological status of the 26 females radically changes the behavioural response. The situation at puberty is somewhat 27 similar: prepubertal females avoid adult male chemical signals, whereas post-pubertal 28 females show attraction for these same signals. In addition, we report another situation in 29 which the presence of darcin is not attractive to adult female mice. Urine of males parasitized 30 by the intestinal nematode Aspiculuris tetraptera shows no attractive value for female mice, 31 despite apparently normal presence of darcin. In this case, the loss of the attractive value is 32 not due to physiological changes in the receptor females but is likely to be due to the 33 presence of unknown signals of infection whose detection overrides the attraction normally 34 induced by darcin. 35 36