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\nIntroduction: The detection of chemical signals by the vomeronasal organ (VNO) is critical for mammals from an early age, influencing behaviors such as suckling and recognition of the mother. Located at the base of the nasal cavity, the VNO features a duct covered with a sensory epithelium. A critical aspect of VNO functionality is the efficient access of stimuli from the nasal and oral cavities to the receptors. In adult dogs, it has been demonstrated how the vomeronasal duct (VD) communicates to the environment through the incisive duct (ID). In newborn puppies, the existence of functional communication between the ID and the VD has not been confirmed to date, raising doubts about the potential physiological obliteration of the ID. Determining this aspect is necessary to evaluate the role played by chemocommunication in the survival and socialization of puppies. Methods: This study employs serial histological staining to examine the presence and functionality of the ID in neonatal dogs. Additionally, a histochemical study was conducted using periodic acid-Schiff and Alcian Blue staining, along with labeling with six lectins to characterize the expression of glycoconjugates in the incisive papilla and in the area between the ID and the VD. Results: The histological study has confirmed both the existence of functional communication between both ducts in perinatal puppies and the dual functional communication of the ID with the oral and nasal cavities. Lectin labeling has allowed for the characterization of the glycoconjugate expression profile in the papilla and ID, showing significant differences between lectins. Conclusion: The ID is associated with a sophisticated cartilaginous complex that prevents its collapse, as well as erectile tissue that acts as a cushion, facilitating its action under pressure induced by sampling behaviors such as tonguing. This investigation demonstrates the communicative capabilities of the VNO during the perinatal stage in dogs. This study examined how newborn puppies use a special structure, the vomeronasal organ (VNO), to detect chemical signals that help them recognize their mother and locate milk. The VNO has a duct connected to the outside through another passage, the incisive duct (ID). While this connection is known in adult dogs, it had not been confirmed in newborns, raising questions about its role in early life. Through detailed tissue analysis, researchers confirmed the presence of this connection in puppies, allowing access to chemical cues from both the nose and mouth. The ID contains structures that keep it open and responsive, along with specific chemicals in the area that may help puppies recognize scents. These findings support the importance of an active VNO for survival and social behavior from birth. [ABSTRACT FROM AUTHOR]

Simple Summary: The accessory olfactory bulb (AOB) helps animals to process chemical signals, such as pheromones and kairomones, that are important for social and reproductive behaviors. This study focuses on the fossorial water vole, a rodent that lives mostly underground and relies on chemical communication. We examined the structure of the AOB in these voles using various staining techniques to visualize different cell types. The results showed that the fossorial water vole AOB has a well-organized structure, with specific cells in different layers. We also found that certain glycans and proteins are more active in the AOB compared to the main olfactory bulb, which suggests that these two areas of the brain have different roles in processing smells. This research helps us understand how the sense of smell of the fossorial water vole is specially adapted to its underground environment. The findings could be useful for further studies on how to manage these vole populations, as their behavior and chemical communication are essential for their survival and interactions in underground environments. The accessory olfactory bulb (AOB) processes chemical signals crucial for species-specific socio-sexual behaviors. There is limited information about the AOB of wild rodents, and this study aims to characterize the neurochemical organization of the AOB in the fossorial water vole (Arvicola scherman), a subterranean Cricetidae rodent. We employed histological, immunohistochemical, and lectin-histochemical techniques. The AOB of these voles exhibits a distinct laminar organization, with prominent mitral cells and a dense population of periglomerular cells. Lectin histochemistry and G-protein immunohistochemistry confirmed the existence of an antero-posterior zonation. Immunohistochemical analysis demonstrated significant expression of PGP 9.5, suggesting its involvement in maintaining neuronal activity within the AOB. In contrast, the absence of SMI-32 labelling in the AOB, compared to its strong expression in the main olfactory bulb, highlights functional distinctions between these two olfactory subsystems. Calcium-binding proteins allowed the characterization of atypical sub-bulbar nuclei topographically related to the AOB. All these features suggest that the AOB of Arvicola scherman is adapted for enhanced processing of chemosensory signals, which may play a pivotal role in its subterranean lifestyle. Our results provide a foundation for future studies exploring the implications of these adaptations, including potential improvements in the management of these vole populations. [ABSTRACT FROM AUTHOR]

The mammalian vomeronasal system enables the perception of chemical signals crucial for social communication via the receptor families V1R and V2R. These receptors are linked with the G-protein subunits, Gαi2 and Gαo, respectively. Exploring the evolutionary pathways of V1Rs and V2Rs across mammalian species remains a significant challenge, particularly when comparing genomic data with emerging immunohistochemical evidence. Recent studies have revealed the expression of Gαo in the vomeronasal neuroepithelium of wild canids, including wolves and foxes, contradicting predictions based on current genomic annotations. Our study provides detailed immunohistochemical evidence, mapping the expression of V2R receptors in the vomeronasal sensory epithelium, focusing particularly on wild canids, specifically wolves and foxes. An additional objective involves contrasting these findings with those from domestic species like dogs to highlight the evolutionary impacts of domestication on sensory systems. The employment of a specific antibody raised against the mouse V2R2, a member of the C-family of vomeronasal receptors, V2Rs, has confirmed the presence of V2R2-immunoreactivity (V2R2-ir) in the fox and wolf, but it has revealed the lack of expression in the dog. This may reflect the impact of domestication on the regression of the VNS in this species, in contrast to their wild counterparts, and it underscores the effects of artificial selection on sensory functions. Thus, these findings suggest a more refined chemical detection capability in wild species. [ABSTRACT FROM AUTHOR]

Dama gazelle is a threatened and rarely studied species found primarily in northern Africa. Human pressure has depleted the dama gazelle population from tens of thousands to a few hundred individuals. Since 1970, a founder population consisting of the last 17 surviving individuals in Western Sahara has been maintained in captivity, reproducing naturally. In preparation for the future implementation of assisted reproductive technology, certain aspects of dama gazelle reproductive biology have been established. However, the role played by semiochemical‐mediated communications in the sexual behavior of dama gazelle remains unknown due partially to a lack of a neuroanatomical or morphofunctional characterization of the dama gazelle vomeronasal organ (VNO), which is the sensory organ responsible for pheromone processing. The present study characterized the dama gazelle VNO, which appears fully equipped to perform neurosensory functions, contributing to current understanding of interspecies VNO variability among ruminants. By employing histological, lectin‐histochemical, and immunohistochemical techniques, we conducted a detailed morphofunctional evaluation of the dama gazelle VNO along its entire longitudinal axis. Our findings of significant structural and neurochemical transformation along the entire VNO suggest that future studies of the VNO should take a similar approach. The present study contributes to current understanding of dama gazelle VNO, providing a basis for future studies of semiochemical‐mediated communications and reproductive management in this species. Research Highlights: This exhaustive immunohistological study of the vomeronasal organ (VNO) of the dama gazelle provides the first evidence of notable differences in the expression of neuronal markers along the rostrocaudal axis of the VNO.This provides a morphological basis for the implementation of pheromones in captive populations of dama gazelle. [ABSTRACT FROM AUTHOR]

Simple Summary: In wild mammals, chemical senses are crucial to survival, but sensory system information is lacking for many species, including the meerkat (Suricata suricatta), an iconic mammal with a marked social hierarchy that has been ambiguously classified in both canid and felid families. We studied the neuroanatomical basis of the meerkat olfactory and accessory olfactory bulbs, aiming to provide information on the relevance of both systems to the behaviors of this species and contributing to improving its taxonomic classification. The accessory olfactory bulb serves as the integration center of vomeronasal information. When examined microscopically, the accessory olfactory bulb of the meerkat presents a lamination pattern more defined than observed in dogs and approaching the pattern described in cats. The degree of lamination and development in the meerkat main olfactory bulb is comparable to the general pattern observed in mammals but with numerous specific features. Our study supports the functionality of the olfactory and vomeronasal integrative centers in meerkats and places this species within the suborder Feliformia. Our study also confirms the importance of chemical signals in mediating the social behaviors of this species and provides essential neuroanatomical information for understanding the functioning of their chemical senses. We approached the study of the main (MOB) and accessory olfactory bulbs (AOB) of the meerkat (Suricata suricatta) aiming to fill important gaps in knowledge regarding the neuroanatomical basis of olfactory and pheromonal signal processing in this iconic species. Microdissection techniques were used to extract the olfactory bulbs. The samples were subjected to hematoxylin-eosin and Nissl stains, histochemical (Ulex europaeus agglutinin, Lycopersicon esculentum agglutinin) and immunohistochemical labelling (Gαo, Gαi2, calretinin, calbindin, olfactory marker protein, glial fibrillary acidic protein, microtubule-associated protein 2, SMI-32, growth-associated protein 43). Microscopically, the meerkat AOB lamination pattern is more defined than the dog's, approaching that described in cats, with well-defined glomeruli and a wide mitral-plexiform layer, with scattered main cells and granular cells organized in clusters. The degree of lamination and development of the meerkat MOB suggests a macrosmatic mammalian species. Calcium-binding proteins allow for the discrimination of atypical glomerular subpopulations in the olfactory limbus between the MOB and AOB. Our observations support AOB functionality in the meerkat, indicating chemosensory specialization for the detection of pheromones, as identified by the characterization of the V1R vomeronasal receptor family and the apparent deterioration of the V2R receptor family. [ABSTRACT FROM AUTHOR]

The fossorial water vole, Arvicola scherman, is an herbivorous rodent that causes significant agricultural damages. The application of cairomones and alarm pheromones emerges as a promising sustainable method to improve its integrated management. These chemical signals would induce stress responses that could interfere with the species regular reproductive cycles and induce aversive reactions, steering them away from farmlands and meadows. However, there is a paucity of information regarding the water vole vomeronasal system, both in its morphological foundations and its functionality, making it imperative to understand the same for the application of chemical communication in pest control. This study fills the existing gaps in knowledge through a morphological and immunohistochemical analysis of the fossorial water vole vomeronasal organ. The study is primarily microscopic, employing two approaches: histological, using serial sections stained with various dyes (hematoxylin-eosin, Periodic acid-Schiff, Alcian blue, Nissl), and immunohistochemical, applying various markers that provide morphofunctional and structural information. These procedures have confirmed the presence of a functional vomeronasal system in fossorial water voles, characterized by a high degree of differentiation and a significant expression of cellular markers indicative of active chemical communication in this species., (© 2023 The Authors. The Anatomical Record published by Wiley Periodicals LLC on behalf of American Association for Anatomy.)