Immunohistological study of the unexplored vomeronasal organ of an endangered mammal, the dama gazelle (Nanger dama)

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 speciesThis work was partially supported by a grant from “Consello Social Universidade de Santiago de Compostela” 2022-PU004S

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

Background: The 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. Methods: A 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. Results: The 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 nervesS

The Risk of Extrapolation in Neuroanatomy: The Case of the Mammalian Vomeronasal System†

The sense of smell plays a crucial role in mammalian social and sexual behaviour, identification of food, and detection of predators. Nevertheless, mammals vary in their olfactory ability. One reason for this concerns the degree of development of their pars basalis rhinencephali, an anatomical feature that has been considered in classifying this group of animals as macrosmatic, microsmatic or anosmatic. In mammals, different structures are involved in detecting odours: the main olfactory system, the vomeronasal system (VNS), and two subsystems, namely the ganglion of Grüneberg and the septal organ. Here, we review and summarise some aspects of the comparative anatomy of the VNS and its putative relationship to other olfactory structures. Even in the macrosmatic group, morphological diversity is an important characteristic of the VNS, specifically of the vomeronasal organ and the accessory olfactory bulb. We conclude that it is a big mistake to extrapolate anatomical data of the VNS from species to species, even in the case of relatively close evolutionary proximity between them. We propose to study other mammalian VNS than those of rodents in depth as a way to clarify its exact role in olfaction. Our experience in this field leads us to hypothesise that the VNS, considered for all mammalian species, could be a system undergoing involution or regression, and could serve as one more integrated olfactory subsystem

Artiodactyl livestock species have a uniform vomeronasal system with a vomeronasal type 1 receptor (V1R) pathway

application/pdfArtiodactyl livestock animals have a vomeronasal system that detects pheromones. Vomeronasal receptors comprise type 1 (V1R) coupled with G protein α-i2 (Gαi2) and type 2 (V2R) coupled with G protein α-o (Gαo). Laboratory rodents have two segregated V1R and V2R pathways that reach separately to the accessory olfactory bulb (AOB). In contrast, the AOBs of goats and sheep are entirely positive for Gαi2, indicating that they have only the V1R pathway. However, we detected a few V2R genes in the genome of cattle, goats, sheep and pigs by genome assembly. Thus, we immunohistochemically analyzed the AOBs of cattle and pigs to confirm which type of the vomeronasal system is present in artiodactyl livestock species. The glomerular layer of the AOB in cattle and pigs was entirely positive for anti-Gαi2 and weakly positive for anti-Gαo, as in the V1R uniform type of vomeronasal system in other mammal species. These findings indicated that artiodactyl livestock species have a uniform type of vomeronasal system composing the V1R pathway. Therefore, caution is advised when extrapolating knowledge of laboratory rodents with two vomeronasal pathways to livestock animals that have one. © 2022 Elsevier Ltdjournal articl

Morphological and histological features of the vomeronasal organ in the brown bear

application/pdfThe vomeronasal organ (VNO) is a peripheral receptor structure that is involved in reproductive behavior and is part of the vomeronasal system. Male bears exhibit flehmen behavior that is regarded as the uptake of pheromones into the VNO to detect estrus in females. However, the morphological and histological features of the VNO in bears have not been comprehensively studied. The present study investigated the properties and degree of development of the VNO of the brown bear by histological, histochemical and ultrastructural methods. The VNO of bears was located at the same position as that of many other mammals, and it opened to the mouth like the VNO of most carnivores. The shape of the vomeronasal cartilages and the histological features of the sensory epithelium in the bear VNO were essentially similar to those of dogs. Receptor cells in the VNO of the bear possessed both cilia and microvilli like those of dogs. The dendritic knobs of receptor cells were positive for anti-G protein alpha-i2 subunit (Gαi2) but negative for anti-G protein alpha-o subunit, indicating preferential use of the V1R-Gαi2 pathway in the vomeronasal system of bears, as in other carnivores. The VNO of the bear possessed three types of secretory cells (secretory cells of the vomeronasal gland, multicellular intraepithelial gland cells and goblet cells), and the present findings showed that the secretory granules in these cells also had various properties. The vomeronasal lumen at the middle region of the VNO invaginated toward the ventral region, and this invagination contained tightly packed multicellular intraepithelial gland cells. To our knowledge, this invagination and intraepithelial gland masses in the VNO are unique features of brown bears. The VNO in the brown bear, especially the secretory system, is morphologically well-developed, suggesting that this organ is significant for information transmission in this species. © 2017 Anatomical Societyjournal articl

Histological features of the vomeronasal organ in the giraffe, Giraffa camelopardalis

application/pdfThe vomeronasal organ (VNO) that preferentially detects species-specific substances is diverse among animal species, and its morphological properties seem to reflect the ecological features of animals. This histological study of two female reticulated giraffes (Giraffa camelopardalis reticulata) found that the VNO is developed in giraffes. The lateral and medial regions of the vomeronasal lumen were covered with sensory and nonsensory epithelia, respectively. The vomeronasal glands were positive for periodic acid-Schiff and alcian blue (pH 2.5) stains. The VNO comprises several large veins like others in the order Cetartiodactyla, suggesting that these veins function in a pumping mechanism in this order. In addition, numerous thin-walled vessels located immediately beneath the epithelia covering the lumen entirely surrounded the vomeronasal lumen. This sponge-like structure might function as a specific secondary pump in giraffes.journal articl

Neuroanatomical and gene expression features of the rabbit accessory olfactory system. Implications of pheromone communication in reproductive behaviour and animal physiology

Mainly driven by the vomeronasal system (VNS), pheromone communication is involved in many species-specific fundamental innate socio-sexual behaviors such as mating and fighting, which are essential for animal reproduction and survival. Rabbits are a unique model for studying chemocommunication due to the discovery of the rabbit mammary pheromone, but paradoxically there has been a lack of knowledge regarding its VNS pathway. In this work, we aim at filling this gap by approaching the system from an integrative point of view, providing extensive anatomical and genomic data of the rabbit VNS, as well as pheromone-mediated reproductive and behavioural studies. Our results build strong foundation for further translational studies which aim at implementing the use of pheromones to improve animal production and welfare

Definición morfológica del epitelio sensorial olfativo en los mamíferos

La cavidad nasal de tres especies de mamíferos macrosmáticos –ratón, perro y oveja– ha sido estudiada morfológicamente de acuerdo con el procedimiento habitual seguido en técnica anatómica, disección y microdisección, así como microscópicamente según aconseja la técnica histológica, cortes seriados teñidos con colorantes básicos, y con el empleo de marcadores para completar el conveniente estudio inmuno-histoquímico. Los receptores sensoriales olfativos del ratón se encuentran localizados en cuatro áreas distintas: el epitelio olfativo principal, el epitelio olfativo secundario o vomeronasal, el epitelio olfativo del órgano septal y en el ganglio de Grüneberg, cuya topografía y otros detalles anatómicos se han representado en un atlas on line: https://www.usc.es/anatembriol/. En los cuatro territorios mencionados las neuronas expresan la proteína específica para el sistema olfativo, OMP, neuronas que también se tiñen cuando se emplea como marcador la lectina Lycopersicum esculentum agglutinin, con la excepción de aquellas pertenecientes al ganglio de Grüneberg. Cuando se emplea como marcador la lectina Ulex europaeus agglutinin I se observa que es específica para el tejido que expresa la proteína Gαi2, es decir neuronas asociadas al sistema vomeronasal. En el perro, con la metodología seguida en este estudio, no fue posible identificar ninguna estructura con las características que definen al órgano septal y al ganglio de Grüneberg en el ratón. Ya que para tal búsqueda se utilizaron animales adultos, recién nacidos y fetos es de suponer que esas dos formaciones no existen en el perro. Asimismo, se constató la falta de componentes vomeronasales asociados a los receptores VR2. Al igual que en el perro, el presente estudio revela que en la oveja tampoco hay ni órgano septal ni ganglio de Grüneberg. En esta especie animal los resultados obtenidos sugieren que las neuronas sensoriales olfativas están fundamentalmente concentradas en el epitelio olfativo principal y en mucha menor proporción en el epitelio sensorial del órgano vomeronasal

Novel Insights into Lectin Binding Patterns in the Nasopharyngeal Tonsil of Buffaloes (Bubalus bubalis)

Background: The present study investigates the specificity of lectin binding in the nasopharyngeal tonsil of six healthy adult buffaloes (Bubalus bubalis), a species not extensively studied regarding its immune system. Lectins, proteins that bind specifically to carbohydrates, are used to identify and characterize different cell types that may have roles in immune responses. This study explores how lectins bind to various cells within the nasopharyngeal tonsil, shedding light on cellular differentiation, interactions, and the potential functional roles of these cells in mucosal immunity. Methods: A total of 21 biotinylated lectins, grouped into five categories based on their carbohydrate specificity (N-acetylglucosamine, N-acetylgalactosamine, galactose, glucose/ mannose, and fucose), were used to probe the nasopharyngeal tonsil tissue. Lectin histochemistry was applied to identify the binding patterns of these lectins to different cell types within the tissue, including epithelial cells, lymphoid cells, and specialized structures such as M-cells and P-cells. The study also involved the detection of vimentin filaments to explore potential immune responses within the tissue. Results: Lectin histochemistry revealed a dynamic epithelial composition of the nasopharyngeal tonsil, consisting of pseudostratified columnar ciliated epithelium and lymphoepithelium, with distinct adaptations in the follicle-associated epithelium (FAE). The FAE exhibited M-cells, which are believed to play a role in antigen processing. Additionally, a new class of cells, termed P-cells, was identified based on their lectin-binding patterns, which share similarities with M-cells but are distinct in their function. Lectins targeting N-acetylglucosamine exhibited varying affinities for M- and P-cells, while lectins recognizing N-acetylgalactosamine selectively bound to cilia and goblet cells. Lectins targeting galactose produced complex staining patterns in mucous glands and lymphoid tissues. Specific binding was also observed in lymphoid cells with lectins recognizing glucose/mannose and fucose groups. Vimentin filaments in lymphocytes and specialized epithelial cells suggest an involvement in immune response mechanisms. Conclusion: This study provides new insights into structural organisation landscape of the buffalo nasopharyngeal tonsil, highlighting the role of lectin-binding patterns in identifying specialized cells and tissues. The M-cells and discovery of P-cells and the detailed lectin-binding profiles may contribute to understanding the cellular dynamics of mucosal immunity. Additionally, the structural details uncovered in this study may serve as a valuable reference for comparative research on mucosal immunity across different species, advancing our understanding of antigen recognition and immune responses at mucosal surfaces

Human cord blood CD1331 stem cells transplanted to nod-scid mice provide conditions for regeneration of olfactory neuroepithelium after permanent damage induced by dichlobenil

none10siThe herbicide dichlobenil selectively causes necrosis of the dorsomedial part of olfactory neuroepithelium (NE) with permanent damage to the underlying mucosa, whereas the lateral part of the olfactory region and the nasal respiratory mucosa remain undamaged. We investigated here whether human umbilical cord blood CD1331 stem cells (HSC) injected intravenously to nod-scid mice pretreated with dichlobenil may engraft the olfactory mucosa and contribute to the regeneration of the damaged NE. We tested HLA-DQa1 DNA and three human microsatellites (Combined DNA Index System) as indicators of engrafted cells, finding polymerase chain reaction evidence of chimaerism in various tissues of the host, including the olfactory mucosa and bulb, at 7 and 31 days following HSC transplantation. Histology, immunohistochemistry, and lectin staining revealed the morphological recovery of the dorsomedial region of the NE in dichlobenil-treated mice that received HSC, contrasting with the lack of regeneration in similarly injured areas as these remained damaged in control nontransplanted mice. FISH analysis, to detect human genomic sequences from different chromosomes, confirmed persistent engraftment of the regenerating olfactory area with chimeric cells. Electro-olfactograms in response to odorants, to test the functionality of the olfactory NE, confirmed the functional damage of the dorsomedial area in dichlobenil- treated mice and the functional recovery of the same area in transplanted mice. These findings support the concept that transplanted HSC migrating to the damaged olfactory area provide conditions facilitating the recovery from olfactory receptor cell loss. © Alphamed Press.openFranceschini V.; Bettini S.; Pifferi S.; Rosellini A.; Menini A.; Saccardi R.; Ognio E.; Jeffery R.; Poulsom R.; Revoltella R.P.Franceschini, V.; Bettini, S.; Pifferi, S.; Rosellini, A.; Menini, A.; Saccardi, R.; Ognio, E.; Jeffery, R.; Poulsom, R.; Revoltella, R. P