Vomeronasal Research Articles

Hemoglobin in the blood acts as a chemosensory signal via the mouse vomeronasal system

The vomeronasal system plays an essential role in sensing various environmental chemical cues. Here we show that mice exposed to blood and, consequently, hemoglobin results in the activation of vomeronasal sensory neurons expressing a specific vomeronasal G protein-coupled receptor, Vmn2r88, which is mediated by the interaction site, Gly17, on hemoglobin. The hemoglobin signal reaches the medial amygdala (MeA) in both male and female mice. However, it activates the dorsal part of ventromedial hypothalamus (VMHd) only in lactating female mice. As a result, in lactating mothers, hemoglobin enhances digging and rearing behavior. Manipulation of steroidogenic factor 1 (SF1)-expressing neurons in the VMHd is sufficient to induce the hemoglobin-mediated behaviors. Our results suggest that the oxygen-carrier hemoglobin plays a role as a chemosensory signal, eliciting behavioral responses in mice in a state-dependent fashion.

Is There a Link between Vomeronasalitis and Aggression in Stable Social Groups of Female Pigs?

Simple SummaryThe vomeronasal organ plays a key role in intraspecific animal behavior since it is able to detect pheromones. Induced and spontaneous lesions of this structure have been previously associated with various social behavior alterations in animals. In cats, the inflammation of this organ, named vomeronasalitis, has been associated with the presence of aggression towards other cats. The aim of this study was to describe this pathology in farm pigs and to evaluate if it is associated with social alterations as described in cats. Our study showed that farm pigs can be affected by the inflammation of the vomeronasal organ and that the pigs with this alteration present an increased number of skin lesions induced by fights with other pigs. These results open an interesting perspective that links the alteration of this organ to the presence of aggressive behaviors in farm animals, which implicates an important issue in animal welfare. The vomeronasal organ (VNO) is a bilateral chemosensory structure strongly involved in animal behaviour, thanks to its sensory epithelium (VNSE) that detects pheromones. Experimental VNO lesions can impair social, reproductive and maternal behaviour, while feline spontaneous vomeronasalitis has been associated with aggression. This study aimed to describe vomeronasalitis in farm pigs and explore its association with intraspecific behavioural alterations. Using 38 six-month-old pigs, the skin lesion score based on Welfare Quality® protocols was obtained during the fattening period. The seventy-six VNOs from these pigs were stained in haematoxylin-eosin for histological examinations. VNSE inflammation was classified considering its intensity. Skin lesions data were compared to vomeronasalitis. There were 34% of pigs that showed unilateral VNSE inflammation, while 66% were bilaterally affected. The mean ± SD number of skin lesions/animal was 4.4 ± 2.82, and 34% of pigs scored 1 (moderately wounded animals) at least once during the fattening period. Statistical analysis showed an association between bilateral vomeronasalitis and skin lesion score (p < 0.05) and between bilateral moderate vomeronasalitis and skin lesions number (p < 0.01). This is the first report linking vomeronasalitis to social life in farm animals. Considering the role of social life in animal welfare, our data opens a research field linking pathology to animal behaviour.

Transcriptome Analysis Reveals Olfactory System Expression Characteristics of Aquatic Snakes.

Animal olfactory systems evolved with changes in habitat to detect odor cues from the environment. The aquatic environment, as a unique habitat, poses a formidable challenge for olfactory perception in animals, since the higher density and viscosity of water. The olfactory system in snakes is highly specialized, thus providing the opportunity to explore the adaptive evolution of such systems to unique habitats. To date, however, few studies have explored the changes in gene expression features in the olfactory systems of aquatic snakes. In this study, we carried out RNA sequencing of 26 olfactory tissue samples (vomeronasal organ and olfactory bulb) from two aquatic and two non-aquatic snake species to explore gene expression changes under the aquatic environment. Weighted gene co-expression network analysis showed significant differences in gene expression profiles between aquatic and non-aquatic habitats. The main olfactory systems of the aquatic and non-aquatic snakes were regulated by different genes. Among these genes, RELN may contribute to exploring gene expression changes under the aquatic environment by regulating the formation of inhibitory neurons in the granular cell layer and increasing the separation of neuronal patterns to correctly identify complex chemical information. The high expression of TRPC2 and V2R family genes in the accessory olfactory systems of aquatic snakes should enhance their ability to bind water-soluble odor molecules, and thus obtain more information in hydrophytic habitats. This work provides an important foundation for exploring the olfactory adaptation of snakes in special habitats.

Histological Features of the Nasal Passage in Juvenile Japanese White Rabbits.

Rabbits are sometimes used for intranasal toxicology studies. We investigated the postnatal development of the nasal passage in juvenile Japanese white rabbits from just after birth to 6-week-old to provide information for conducting intranasal toxicological evaluation using juvenile animals. On postnatal day (PND) 1, the nasal passage consisted of the septum with mostly cartilaginous nasal wall and turbinates. The lining squamous, transitional, respiratory, and olfactory epithelia were already distributed similar to adults and were still underdeveloped. The nasal passage gradually expanded with age, as did the nasal wall, including the turbinates formed by endochondral ossification. The maxilloturbinate elongated, during which it branched complexly. The respiratory epithelium takes the form of columnar epithelium together with a reduction in goblet cells. In addition, the olfactory epithelium had clear cytoplasm in the ethmoturbinate, the olfactory nerve bundles thickened, and Bowman's gland acini increased in size and number. Other tissues, including the vomeronasal organ, nasal-associated lymphoid tissue, and nasolacrimal duct, also developed histologically with age. This investigation characterized the postnatal histological development of the nasal passage in Japanese white rabbits, providing basic knowledge regarding the histological examination and rationale for appropriate study design of intranasal toxicology studies in juvenile rabbits.

Distribution of recesses in the olfactory organ of African lungfish Protopterus aethiopicus.

In the olfactory organ of lungfish, recesses at the bases of lamellae comprise sensory and nonsensory epithelia. The sensory epithelium of the recesses, the recess epithelium, is distinguished from the olfactory epithelium covering the lamella by the absence of ciliated olfactory receptor cells. Therefore, it has been suggested that the recess epithelium is a primordium of the vomeronasal organ of tetrapods. However, developmental changes in the number and distribution of recesses in the olfactory organ of lungfish were unknown. We examined four Protopterus aethiopicus specimens of body lengths 215–800 mm to determine the localization of recesses in their olfactory organs. Histological examination showed recesses at the bases of lamellae in all individuals examined. The recesses were localized mainly in the medial and caudal parts of the olfactory organs, especially in juveniles. Compared to smaller fish, larger fish had a larger number of recesses, distributed more broadly in their olfactory organs. Significance of the recess localization and its relationship to the function of lungfish olfactory organ warrants further investigation.

Histology and lectin histochemistry in the vomeronasal organ of Korean native cattle, Bos taurus coreanae

Histology and lectin histochemistry in the vomeronasal organ of Korean native cattle, <i>Bos taurus coreanae</i>

The incisive foramen as character in distinguishing morphologically similar species of mammals

An analysis of the morphology and variability of the size and shape of a key morphological structure in the rostral part of the skull—the incisive foramen—has been carried out. It is shown that incisive foramina are variable morphological structures, the features of which are group-specific (at the level of genera and families), and in some cases also species-specific. At both these levels, the shape and size of the incisive foramen have features that can serve as criteria for species identification by osteological patterns. Their location is important for diagnosis because these structures are preserved in most specimens that have suffered various kinds of damage (e.g. in fodder residues of carnivorous mammals or in owl pellets), and their placement in the anterior part of the bony palate as well as them being protected from the sides with rows of teeth makes these structures invulnerable to trauma-related variation. It is shown that there is a specific structure (size, location, and shape) of incisive foramina at the level of taxonomic groups of all ranks, from orders to species. The analysis was performed mainly on the examples of different groups of rodents as an order, represented by the largest number of pairs of close species. Examples with several different groups, in particular with different pairs of species of voles, mice, mole rats, ground squirrels, and others are considered. Examples with differences in close pairs of species in other groups (white-toothed shrews, polecats, roe deer, etc.) are also known. In all pairs of related species, a pattern was found, according to which species that are restricted to steppe ecosystems have the smallest incisive foramina, while species from wetland habitats have large ones. In many cases, groups of genera and families well differ in the shape and location of incisive foramina, and close pairs of species differ well in the size of these structures (primarily in length), although it is important to always consider the ontogenetic age of specimens: in young individuals, the incisive foramina are naturally small, similar to incisive foramina in other species, which are characterized by small incisive foramina in general. Based on the known data on the role of incisive foramina and the Jacobson organ in the life of mammals, hypotheses have been considered that may explain the differences in species and genera by the structure (size, location, and shape) of incisive foramina.

How the evolution of air breathing shaped hippocampal function.

To make maps from airborne odours requires dynamic respiratory patterns. I propose that this constraint explains the modulation of memory by nasal respiration in mammals, including murine rodents (e.g. laboratory mouse, laboratory rat) and humans. My prior theories of limbic system evolution offer a framework to understand why this occurs. The answer begins with the evolution of nasal respiration in Devonian lobe-finned fishes. This evolutionary innovation led to adaptive radiations in chemosensory systems, including the emergence of the vomeronasal system and a specialization of the main olfactory system for spatial orientation. As mammals continued to radiate into environments hostile to spatial olfaction (air, water), there was a loss of hippocampal structure and function in lineages that evolved sensory modalities adapted to these new environments. Hence the independent evolution of echolocation in bats and toothed whales was accompanied by a loss of hippocampal structure (whales) and an absence of hippocampal theta oscillations during navigation (bats). In conclusion, models of hippocampal function that are divorced from considerations of ecology and evolution fall short of explaining hippocampal diversity across mammals and even hippocampal function in humans.This article is part of the theme issue ‘Systems neuroscience through the lens of evolutionary theory’.

Can domestication shape Canidae brain morphology? The accessory olfactory bulb of the red fox as a case in point

BackgroundThe accessory olfactory bulb (AOB) is the first integrative center of the vomeronasal system (VNS), and the general macroscopic, microscopic, and neurochemical organizational patterns of the AOB differ fundamentally among species. Therefore, the low degree of differentiation observed for the dog AOB is surprising. As the artificial selection pressure exerted on domestic dogs has been suggested to play a key role in the involution of the dog VNS, a wild canid, such as the fox, represents a useful model for studying the hypothetical effects of domestication on the AOB morphology. MethodsA comprehensive histological, lectin-histochemical, and immunohistochemical study of the fox AOB was performed. Anti-Gαo and anti-Gαi2 antibodies were particularly useful, as they label the transduction cascade of the vomeronasal receptor types 1 (V1R) and 2 (V2R), respectively. Other employed antibodies included those against proteins such as microtubule-associated protein 2 (MAP-2), tubulin, glial fibrillary acidic protein, growth-associated protein 43 (GAP-43), olfactory marker protein (OMP), calbindin, and calretinin. ResultsThe cytoarchitecture of the fox AOB showed a clear lamination, with neatly differentiated layers; a highly developed glomerular layer, rich in periglomerular cells; and large inner cell and granular layers. The immunolabeling of Gαi2, OMP, and GAP-43 delineated the outer layers, whereas Gαo and MAP-2 immunolabeling defined the inner layers. MAP-2 characterized the somas of AOB principal cells and their dendritic trees. Anti-calbindin and anti-calretinin antibodies discriminated neural subpopulations in both the mitral-plexiform layer and the granular cell layer, and the lectin Ulex europeus agglutinin I (UEA-I) showed selectivity for the AOB and the vomeronasal nerves. ConclusionThe fox AOB presents unique characteristics and a higher degree of morphological development compared with the dog AOB. The comparatively complex neural basis for semiochemical information processing in the fox compared with that observed in dogs suggests loss of AOB anatomical complexity during the evolutionary history of dogs and opens a new avenue of research for studying the effects of domestication on brain structures.

Does a third intermediate model for the vomeronasal processing of information exist? Insights from the macropodid neuroanatomy

The study of the α-subunit of Gi2 and Go proteins in the accessory olfactory bulb (AOB) was crucial for the identification of the two main families of vomeronasal receptors, V1R and V2R. Both families are expressed in the rodent and lagomorph AOBs, according to a segregated model characterized by topographical anteroposterior zonation. Many mammal species have suffered from the deterioration of the Gαo pathway and are categorized as belonging to the uniform model. This scenario has been complicated by characterization of the AOB in the tammar wallaby, Notamacropus eugenii, which appears to follow a third model of vomeronasal organization featuring exclusive Gαo protein expression, referred to as the intermediate model, which has not yet been replicated in any other species. Our morphofunctional study of the vomeronasal system (VNS) in Bennett’s wallaby, Notamacropus rufogriseus, provides further information regarding this third model of vomeronasal transduction. A comprehensive histological, lectin, and immunohistochemical study of the Bennett’s wallaby VNS was performed. Anti-Gαo and anti-Gαi2 antibodies were particularly useful because they labeled the transduction cascade of V2R and V1R receptors, respectively. Both G proteins showed canonical immunohistochemical labeling in the vomeronasal organ and the AOB, consistent with the anterior–posterior zonation of the segregated model. The lectin Ulex europaeus agglutinin selectively labeled the anterior AOB, providing additional evidence for the segregation of vomeronasal information in the wallaby. Overall, the VNS of the Bennett’s wallaby shows a degree of differentiation and histochemical and neurochemical diversity comparable to species with greater VNS development. The existence of the third intermediate type in vomeronasal information processing reported in Notamacropus eugenii is not supported by our lectin-histochemical and immunohistochemical findings in Notamacropus rufogriseus.

Spatiotemporal Protein Expression Profiles of QSOX1 in the Murine Uterus, Placenta, and Embryo during Pregnancy

Quiescin Q6 sulfhydryl oxidase 1 (QSOX1) catalyzes the oxidation of the sulfhydryl group to disulfide bond and is widely expressed in various tissues. This study focuses on investigating QSOX1′s spatiotemporal and cellular protein expression profile of the pregnant uterus, placenta, and developing embryo during mouse pregnancy. Immunohistochemical staining was used to reveal the localization of QSOX1 protein, and HistoQuest was applied to quantify protein levels. The expression level of QSOX1 in the decidua and muscle cells of the pregnant uterus fluctuated dramatically during pregnancy. QSOX1 was ubiquitously expressed in the labyrinth, junction zone, and chorionic plate in the placenta. The quantitative analysis found that this protein was highly expressed in the spinal cord, lens, midbrain, cerebellum, medulla oblongata, and tooth of mouse embryos, followed by the heart, intercostal muscle, diaphragm, intermediate zone, extrinsic ocular muscle, spine, pons, epidermis, tongue, ganglion, vomeronasal organ, thoracic vertebrae, and thymus. Interestingly, QSOX1 was also markedly expressed in olfactory system tissues. This comprehensive spatiotemporal study of QSOX1 protein expression will provide a basis for further investigations of the QSOX1 physiological function in the pregnant uterus, placenta, and developing embryo.

Survey anatomy and histological observation of the nasal cavity of Tupaia belangeri chinensis (Tupaiidae, Scandentia, Mammalia)

This study aimed to provide researchers with an atlas of the survey anatomy, histology, and imaging of the nasal cavity of Tupaia belangeri chinensis. Seven T. b. chinensis adult males were euthanized and scanned using micro-computed tomography (CT). The nose was separated, and tissue sections were made on the coronal and axial planes to observe the survey anatomy and histological and imaging characteristics of the nose. T. b. chinensis contains one maxilloturbinal and three ethmoturbinals, one nasoturbinal, one interturbinal, two frontoturbinals, and one lamina semicircularis in the unilateral nasal cavity. Other identified structures were the ostiomeatal complex, vomeronasal organ, superior nasal vault, maxillary sinus, and frontal recess. The drainage pathways of the sinuses and nasal airflow in T. b. chinensis were confirmed. The vault epithelium consisted of the squamous epithelium, respiratory epithelium, transitional epithelium, and olfactory epithelium. Micro-CT confirmed our findings of the coronal tissue sections. The nasal cavity anatomy of T. b. chinensis is similar to that of some strepsirrhine primates. However, the airflow and olfactory function are quite different from that of humans. Our gross and histological atlas of the nasal septum, turbinals, maxillary sinus, and frontal recess provides a reference for researchers to use T. b. chinensis for nasal cavity functional research.

Spatiotemporal expression of IgLON family members in the developing mouse nervous system

Differential expression of cell adhesion molecules in neuronal populations is one of the many mechanisms promoting the formation of functional neural circuits in the developing nervous system. The IgLON family consists of five cell surface immunoglobulin proteins that have been associated with various developmental disorders, such as autism spectrum disorder, schizophrenia, and major depressive disorder. However, there is still limited and fragmented information about their patterns of expression in certain regions of the developing nervous system and how their expression contributes to their function. Utilizing an in situ hybridization approach, we have analyzed the spatiotemporal expression of all IgLON family members in the developing mouse brain, spinal cord, eye, olfactory epithelium, and vomeronasal organ. At one prenatal (E16) and two postnatal (P0 and P15) ages, we show that each IgLON displays distinct expression patterns in the olfactory system, cerebral cortex, midbrain, cerebellum, spinal cord, and eye, indicating that they likely contribute to the wiring of specific neuronal circuitry. These analyses will inform future functional studies aimed at identifying additional roles for these proteins in nervous system development.

Venous networks in the upper airways of bats: A histological and diceCT study.

Our knowledge of nasal cavity anatomy has grown considerably with the advent of micro-computed tomography (CT). More recently, a technique called diffusible iodine-based contrast-enhanced CT (diceCT) has rendered it possible to study nasal soft tissues. Using diceCT and histology, we aim to (a) explore the utility of these techniques for inferring the presence of venous sinuses that typify respiratory mucosa and (b) inquire whether distribution of vascular mucosa may relate to specialization for derived functions of the nasal cavity (i.e., nasal-emission of echolocation sounds) in bats. Matching histology and diceCT data indicate that diceCT can detect venous sinuses as either darkened, "empty" spaces, or radio-opaque islands when blood cells are present. Thus, we show that diceCT provides reliable information on vascular distribution in the mucosa of the nasal airways. Among the bats studied, a nonecholocating pteropodid (Cynopterus sphinx) and an oral-emitter of echolocation sounds (Eptesicus fuscus) possess venous sinus networks that drain into the sphenopalatine vein rostral to the nasopharynx. In contrast, nasopharyngeal passageways of nasal-emitting hipposiderids are notably packed with venous sinuses. The mucosae of the nasopharyngeal passageways are far less vascular in nasal-emitting phyllostomids, in which vascular mucosae are more widely distributed in the nasal cavity, and in some nectar-feeding species, a particularly large venous sinus is adjacent to the vomeronasal organ. Therefore, we do not find a common pattern of venous sinus distribution associated with nasal emission of sounds in phyllostomids and hipposiderids. Instead, vascular mucosa is more likely critical for air-conditioning and sometimes vomeronasal function in all bats.

Transient Receptor Potential channels (TRP) in GtoPdb v.2021.3

Transient Receptor Potential channels (TRP) in GtoPdb v.2021.3

TMEM16A and TMEM16B Modulate Pheromone-Evoked Action Potential Firing in Mouse Vomeronasal Sensory Neurons

The mouse vomeronasal system controls several social behaviors. Pheromones and other social cues are detected by sensory neurons in the vomeronasal organ (VNO). Stimuli activate a transduction cascade that leads to membrane potential depolarization, increase in cytosolic Ca2+ level, and increased firing. The Ca2+-activated chloride channels TMEM16A and TMEM16B are co-expressed within microvilli of vomeronasal neurons, but their physiological role remains elusive. Here, we investigate the contribution of each of these channels to vomeronasal neuron firing activity by comparing wild-type (WT) and knock-out (KO) mice. Performing loose-patch recordings from neurons in acute VNO slices, we show that spontaneous activity is modified by Tmem16a KO, indicating that TMEM16A, but not TMEM16B, is active under basal conditions. Upon exposure to diluted urine, a rich source of mouse pheromones, we observe significant changes in activity. Vomeronasal sensory neurons (VSNs) from Tmem16a cKO and Tmem16b KO mice show shorter interspike intervals (ISIs) compared with WT mice, indicating that both TMEM16A and TMEM16B modulate the firing pattern of pheromone-evoked activity in VSNs.

Morphological Characteristics and Embryogenesis of the Vomeronasal Organ and Associated Structures in the Japanese Grass Lizard, Takydromus tachydromoides (Squamata: Lacertoidea: Lacertidae)

Squamate reptiles rely on the vomeronasal organ for chemoperception of their environment. This organ functionally associates with several structures, such as the nasolacrimal duct and choanal groove, which are morphologically diverse among species. In this study, we investigated the morphological characteristics and embryogenesis of the vomeronasal organ and its associated structures in the Japanese Grass Lizard (Takydromus tachydromoides). Separation of the complex of the nasolacrimal duct from the vomeronasal organ was observed in this species, a characteristic morphological feature among squamates. Additionally, we integrated the morphological characteristics of the vomeronasal organ and associated structures among squamates, focusing on topological relationships among the structures. The parsimony and likelihood methods for ancestral state reconstruction suggested the parallelism of several morphological characteristics during the evolutionary history of squamates: loss or reduction of the choanal groove, fusion between the nasolacrimal duct and choanal groove, and separation of the nasolacrimal duct from the vomeronasal organ.

The Microvillar and Solitary Chemosensory Cells as the Novel Targets of Infection of SARS-CoV-2 in Syrian Golden Hamsters

Patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019, suffer from respiratory and non-respiratory symptoms. Among these symptoms, the loss of smell has attracted considerable attention. The objectives of this study were to determine which cells are infected, what happens in the olfactory system after viral infection, and how these pathologic changes contribute to olfactory loss. For this purpose, Syrian golden hamsters were used. First, we verified the olfactory structures in the nasal cavity of Syrian golden hamsters, namely the main olfactory epithelium, the vomeronasal organ, and their cellular components. Second, we found angiotensin-converting enzyme 2 expression, a receptor protein of SARS-CoV-2, in both structures and infections of supporting, microvillar, and solitary chemosensory cells. Third, we observed pathological changes in the infected epithelium, including reduced thickness of the mucus layer, detached epithelia, indistinct layers of epithelia, infiltration of inflammatory cells, and apoptotic cells in the overall layers. We concluded that a structurally and functionally altered microenvironment influences olfactory function. We observed the regeneration of the damaged epithelium, and found multilayers of basal cells, indicating that they were activated and proliferating to reconstitute the injured epithelium.

Pannexin 3 channels in health and disease.

Pannexin 3 (PANX3) is a member of the pannexin family of single membrane channel-forming glycoproteins. Originally thought to have a limited localization in cartilage, bone, and skin, PANX3 has now been detected in a variety of other tissues including skeletal muscle, mammary glands, the male reproductive tract, the cochlea, blood vessels, small intestines, teeth, and the vomeronasal organ. In many cell types of the musculoskeletal system, such as osteoblasts, chondrocytes, and odontoblasts, PANX3 has been shown to regulate the balance of proliferation and differentiation. PANX3 can be induced during progenitor cell differentiation, functioning at the cell surface as a conduit for ATP and/or in the endoplasmic reticulum as a calcium leak channel. Evidence in osteoblasts and monocytes also highlight a role for PANX3 in purinergic signalling through its function as an ATP release channel. PANX3 is critical in the development and ageing of bone and cartilage, with its levels temporally regulated in other tissues such as skeletal muscle, skin, and the cochlea. In diseases such as osteoarthritis and intervertebral disc degeneration, PANX3 can have either protective or detrimental roles depending on if the disease is age-related or injury-induced. This review will discuss PANX3 function in tissue growth and regeneration, its role in cellular differentiation, and how it becomes dysregulated in disease conditions such as obesity, Duchenne's muscular dystrophy, osteosarcoma, and non-melanoma skin cancer, where most of the findings on PANX3 function can be attributed to the characterization of Panx3 KO mouse models.

Do all mice smell the same? Chemosensory cues from inbred and wild mouse strains elicit stereotypic sensory representations in the accessory olfactory bulb

BackgroundFor many animals, chemosensory cues are vital for social and defensive interactions and are primarily detected and processed by the vomeronasal system (VNS). These cues are often inherently associated with ethological meaning, leading to stereotyped behaviors. Thus, one would expect consistent representation of these stimuli across different individuals. However, individuals may express different arrays of vomeronasal sensory receptors and may vary in the pattern of connections between those receptors and projection neurons in the accessory olfactory bulb (AOB). In the first part of this study, we address the ability of individuals to form consistent representations despite these potential sources of variability. The second part of our study is motivated by the fact that the majority of research on VNS physiology involves the use of stimuli derived from inbred animals. Yet, it is unclear whether neuronal representations of inbred-derived stimuli are similar to those of more ethologically relevant wild-derived stimuli.ResultsFirst, we compared sensory representations to inbred, wild-derived, and wild urine stimuli in the AOBs of males from two distinct inbred strains, using them as proxies for individuals. We found a remarkable similarity in stimulus representations across the two strains. Next, we compared AOB neuronal responses to inbred, wild-derived, and wild stimuli, again using male inbred mice as subjects. Employing various measures of neuronal activity, we show that wild-derived and wild stimuli elicit responses that are broadly similar to those from inbred stimuli: they are not considerably stronger or weaker, they show similar levels of sexual dimorphism, and when examining population-level activity, cluster with inbred mouse stimuli.ConclusionsDespite strain-specific differences and apparently random connectivity, the AOB can maintain stereotypic sensory representations for broad stimulus categories, providing a substrate for common stereotypical behaviors. In addition, despite many generations of inbreeding, AOB representations capture the key ethological features (i.e., species and sex) of wild-derived and wild counterparts. Beyond these broad similarities, representations of stimuli from wild mice are nevertheless distinct from those elicited by inbred mouse stimuli, suggesting that laboratory inbreeding has indeed resulted in marked modifications of urinary secretions.