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Abo-Ahmed AI, Eshrah EA, Latifi F. Unique nasal septal island in dromedary camels may play a role in pain perception: microscopic studies. Saudi J Biol Sci 2021; 28:3806-3815. [PMID: 34220235 PMCID: PMC8241622 DOI: 10.1016/j.sjbs.2021.03.057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 03/20/2021] [Accepted: 03/22/2021] [Indexed: 12/13/2022] Open
Abstract
The septal island in dromedaries is a distinctive anatomical structure. It has a curiously rostral location and innervated by the trigeminal nerve. It has an unusual ultrastructure and may be specialized for nociception.
The septal organs are islands or patches of sensory epithelium, located in the ventral parts of the nasal septum and innervated by the olfactory nerve. The septal island in dromedaries (Camelus dromedarius) was unusually located in the rostro-dorsal part of the nasal septum, where the ethmoidal branch of the trigeminal nerve provides innervation to the island mucosa. Therefore, the objectives of this study were to reveal the microscopic and ultrastructure of this island and to explain the probable functions. Twelve septal islands from 12 healthy male camels were used. Unlike the olfactory epithelium, which has a pseudostratified structure, the island neuroepithelium had a true neural lamination. Furthermore, in electron micrographs, the receptor, bipolar, and basal cells were connected with an orderly, organized network of cell–cell communication, which had some spine synapses. This network substituted the absence of supporting cells, maintained the shape of the tissue, and held the cells together. Moreover, the receptor cells were not similar to any of the different types of olfactory sensory neurons. Instead, they possessed the apical domain that might be specialized for the detection of chemical stimuli. Interestingly, a resident population of immune cells, namely mast cells and macrophages, was observed. The probable functions were discussed based on the cellular context and architecture. The nasal septal island in dromedaries may have a role in pain perception. The receptor cells most probably work as nociceptive cells that interact with the resident immune cells to coordinate pain signaling with immune response.
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Affiliation(s)
- Ahmed I Abo-Ahmed
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Benha University, Toukh 13736, Egypt
| | - Eman A Eshrah
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Benha University, Toukh 13736, Egypt
| | - Fatgzim Latifi
- Department of Veterinary Medicine, Faculty of Agriculture and Veterinary, University of Prishtina "Hasan Prishtina", Prishtina, Kosovo
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Barrios AW, Sanchez Quinteiro P, Salazar I. The nasal cavity of the sheep and its olfactory sensory epithelium. Microsc Res Tech 2014; 77:1052-9. [PMID: 25213000 DOI: 10.1002/jemt.22436] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 08/31/2014] [Indexed: 11/11/2022]
Abstract
Macro and microdissection methods, conventional histology and immunohistochemical procedures were used to investigate the nasal cavity and turbinate complex in fetal and adult sheep, with special attention to the ethmoturbinates, the vestibular mucosa, and the septal mucosa posterior to the vomeronasal organ. The ectoturbinates, which are variable in number and size, emerge and develop later than the endoturbinates. The olfactory sensory epithelium is composed of basal cells, neurons, and sustentacular cells organized in strata, but numerous different types are distinguishable on the basis of their thickness and other properties; all variants are present on the more developed turbinates, endoturbinates II and III. Mature neurons and olfactory nerve bundles express olfactory marker protein. We found no structure with the characteristics that in mouse define the septal organ or the ganglion of Grüneberg. Our results thus suggest that in sheep olfactory sensory neurons are exclusively concentrated in the main olfactory epithelium and (to a lesser extent) in the vomeronasal organ.
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Affiliation(s)
- Arthur William Barrios
- Department of Anatomy and Animal Production, Unit of Anatomy and Embryology, Faculty of Veterinary, University of Santiago de Compostela, 27002, Lugo, Spain
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Abstract
The olfactory receptor organs and their primary centers are classified into
several types. The receptor organs are divided into fish-type olfactory epithelium (OE),
mammal-type OE, middle chamber epithelium (MCE), lower chamber epithelium (LCE), recess
epithelium, septal olfactory organ of Masera (SO), mammal-type vomeronasal organ (VNO) and
snake-type VNO. The fish-type OE is observed in flatfish and lungfish, while the
mammal-type OE is observed in amphibians, reptiles, birds and mammals. The MCE and LCE are
unique to Xenopus and turtles, respectively. The recess epithelium is
unique to lungfish. The SO is observed only in mammals. The mammal-type VNO is widely
observed in amphibians, lizards and mammals, while the snake-type VNO is unique to snakes.
The VNO itself is absent in turtles and birds. The mammal-type OE, MCE, LCE and recess
epithelium seem to be descendants of the fish-type OE that is derived from the putative
primitive OE. The VNO may be derived from the recess epithelium or fish-type OE and
differentiate into the mammal-type VNO and snake-type VNO. The primary olfactory centers
are divided into mammal-type main olfactory bulbs (MOB), fish-type MOB and mammal-type
accessory olfactory bulbs (AOB). The mammal-type MOB first appears in amphibians and
succeeds to reptiles, birds and mammals. The fish-type MOB, which is unique to fish, may
be the ancestor of the mammal-type MOB. The mammal-type AOB is observed in amphibians,
lizards, snakes and mammals and may be the remnant of the fish-type MOB.
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Affiliation(s)
- Kazuyuki Taniguchi
- Laboratory of Veterinary Anatomy, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan
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Nakamuta S, Nakamuta N, Taniguchi K, Taniguchi K. Localization of the primordial vomeronasal organ and its relationship to the associated gland in lungfish. J Anat 2013; 222:481-5. [PMID: 23368671 DOI: 10.1111/joa.12025] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2013] [Indexed: 11/30/2022] Open
Abstract
The lungfish, the closest fish to tetrapods, has two types of sensory epithelia in the olfactory organ: the lamellar olfactory epithelium and the recess epithelium. The former resembles the olfactory epithelium of ordinary teleosts and the latter resembles the vomeronasal organ of tetrapods with respect to the G-protein expressions and the morphological properties of olfactory receptor cells. In contrast to the lamellar olfactory epithelium covering the surface of olfactory lamella, the recess epithelium, together with the glandular epithelium, lines the recesses at the base of olfactory lamellae and is separated from the surrounding tissues by nonsensory epithelium. In the present study, we examined the distribution of these recesses and the relationship between the recess epithelium and the associated gland in the nasal sac of lungfish. We found that the posterior part of the nasal sac contained more recesses than the anterior one, and the medial one contained more recesses than the lateral one. In addition, virtually all recesses consisted of both the recess epithelium and the glandular epithelium. Furthermore, the glandular epithelium was invariably situated proximal to the midline raphe of the nasal sac, and the recess epithelium distal to it. Possible roles of the recess epithelium and the glandular epithelium are discussed.
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Affiliation(s)
- Shoko Nakamuta
- Laboratory of Veterinary Anatomy, Faculty of Agriculture, Iwate University, Morioka, Japan
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Taniguchi K, Saito S, Taniguchi K. Phylogenic outline of the olfactory system in vertebrates. J Vet Med Sci 2010; 73:139-47. [PMID: 20877153 DOI: 10.1292/jvms.10-0316] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Phylogenic outline of the vertebrate olfactory system is summarized in the present review. In the fish and the birds, the olfactory system consists only of the olfactory epithelium (OE) and the olfactory bulb (B). In the amphibians, reptiles and mammals, the olfactory system is subdivided into the main olfactory and the vomeronasal olfactory systems, and the former consists of the OE and the main olfactory bulb (MOB), while the latter the vomeronasal organ (VNO) and the accessory olfactory bulb (AOB). The subdivision of the olfactory system into the main and the vomeronasal olfactory systems may partly be induced by the difference between paraphyletic groups and monophyletic groups in the phylogeny of vertebrates.
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Affiliation(s)
- Kazumi Taniguchi
- School of Veterinary Medicine and Animal Sciences, Kitasato University, Towada, Japan.
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Taniguchi K, Saito S, Oikawa T, Taniguchi K. Phylogenic aspects of the amphibian dual olfactory system. J Vet Med Sci 2008; 70:1-9. [PMID: 18250565 DOI: 10.1292/jvms.70.1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The phylogenic significance of the subdivision of dual olfactory system is reviewed mainly on the basis of our findings by electron microscopy and lectin histochemistry in the three amphibian species. The dual olfactory system is present in common in these species and consists of the projection from the olfactory epithelium (OE) to the main olfactory bulb (MOB) and that from the vomeronasal epithelium (VNE) to the accessory olfactory bulb (AOB). The phylogenic significance of subdivisions in the dual olfactory system in the amphibian must differently be interpreted. The subdivision of the MOB into its dorsal region (D-MOB) and ventral region (V-MOB) in Xenopus laevis must be attributed to the primitive features in their olfactory receptors. The middle cavity epithelium lining the middle cavity of this frog possesses both ciliated sensory cells and microvillous sensory cells, reminding the OE in fish. The subdivision of the AOB into the rostral (R-AOB) and caudal part (C-AOB) in Bufo japonicus formosus must be regarded as an advanced characteristic. The lack of subdivisions in both MOB and AOB in Cynops pyrrhogaster may reflect their phylogenic primitiveness. Since our lectin histochemistry to detect glycoconjugates expressed in the olfactory pathway reveals the subdivisions in the dual olfactory system in the amphibian, the glycoconjugates may deeply participate in the organization and function of olfactory pathways in phylogeny.
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Affiliation(s)
- Kazumi Taniguchi
- Laboratory of Veterinary Anatomy, School of Veterinary Medicine, Kitasato University, Towada, Japan.
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Abstract
The septal organ, a distinct chemosensory organ observed in the mammalian nose, is essentially a small island of olfactory neuroepithelium located bilaterally at the ventral base of the nasal septum. Virtually nothing is known about its physiological properties and function. To understand the nature of the sensory neurons in this area, we studied the mechanisms underlying olfactory signal transduction in these neurons. The majority of the sensory neurons in the septal organ express olfactory-specific G-protein and adenylyl cyclase type III, suggesting that the cAMP signaling pathway plays a critical role in the septal organ as in the main olfactory epithelium (MOE). This is further supported by patch-clamp recordings from individual dendritic knobs of the sensory neurons in the septal organ. Odorant responses can be mimicked by an adenylyl cyclase activator and a phosphodiesterase inhibitor, and these responses can be blocked by an adenylyl cyclase inhibitor. There is a small subset of cells in the septal organ expressing a cGMP-stimulated phosphodiesterase (phosphodiesterase 2), a marker for the guanylyl cyclase-D subtype sensory neurons identified in the MOE. The results indicate that the septal organ resembles the MOE in major olfactory signal transduction pathways, odorant response properties, and projection to the main olfactory bulb. Molecular and functional analysis of the septal organ, which constitutes approximately 1% of the olfactory epithelium, will provide new insights into the organization of the mammalian olfactory system and the unique function this enigmatic organ may serve.
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Oikawa T, Saito H, Taniguchi K, Taniguchi K. Immunohistochemical studies on the differential maturation of three types of olfactory organs in the rats. J Vet Med Sci 2001; 63:759-65. [PMID: 11503903 DOI: 10.1292/jvms.63.759] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Differential maturation of three types of olfactory organs, the olfactory epithelium (OE), the vomeronasal organ (VNO) and the septal olfactory organ of Masera (MO), was examined immunohistochemically in embryonic and newborn rats by the use of antiprotein gene product 9.5 (PGP 9.5) serum. These olfactory organs were derived in common from the olfactory placode as neuroepithelia. In the OE, PGP 9.5-immunopositive olfactory cells first appeared at 13 days of gestation. The OE maturated completely, and showed the same cytological features as in the adult at 20 days of gestation. The MO first appeared as a dense mass of PGP 9.5-immunopositive sensory cells on the most ventrocaudal part of the nasal septum at 15 days of gestation and was evidently isolated from the OE by the decrease of immunopositive cells in the intercalated epithelium between the OE and the MO at 20 days of gestation. However, even at 7 days after birth, the MO did not complete its development and contained sensory cells aggregating in the mass. The VNO was separated from the nasal cavity at 13 days of gestation as a tubular structure of a neuroepithelium including PGP 9.5-immunopositive sensory cells. These cells gradually increased in number in the sensory epithelium of the VNO and extended their dendritic processes to the free surface at 7 days after birth. These findings clarified the differential maturation of these olfactory organs. That is, the OE completes its development before birth, while the MO and VNO after birth.
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Affiliation(s)
- T Oikawa
- Department of Veterinary Anatomy, Faculty of Agriculture, Iwate University, Morioka, Japan
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Feron VJ, Arts JH, Kuper CF, Slootweg PJ, Woutersen RA. Health risks associated with inhaled nasal toxicants. Crit Rev Toxicol 2001; 31:313-47. [PMID: 11405443 DOI: 10.1080/20014091111712] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Health risks of inhaled nasal toxicants were reviewed with emphasis on chemically induced nasal lesions in humans, sensory irritation, olfactory and trigeminal nerve toxicity, nasal immunopathology and carcinogenesis, nasal responses to chemical mixtures, in vitro models, and nasal dosimetry- and metabolism-based extrapolation of nasal data in animals to humans. Conspicuous findings in humans are the effects of outdoor air pollution on the nasal mucosa, and tobacco smoking as a risk factor for sinonasal squamous cell carcinoma. Objective methods in humans to discriminate between sensory irritation and olfactory stimulation and between adaptation and habituation have been introduced successfully, providing more relevant information than sensory irritation studies in animals. Against the background of chemoperception as a dominant window of the brain on the outside world, nasal neurotoxicology is rapidly developing, focusing on olfactory and trigeminal nerve toxicity. Better insight in the processes underlying neurogenic inflammation may increase our knowledge of the causes of the various chemical sensitivity syndromes. Nasal immunotoxicology is extremely complex, which is mainly due to the pivotal role of nasal lymphoid tissue in the defense of the middle ear, eye, and oral cavity against antigenic substances, and the important function of the nasal passages in brain drainage in rats. The crucial role of tissue damage and reactive epithelial hyperproliferation in nasal carcinogenesis has become overwhelmingly clear as demonstrated by the recently developed biologically based model for predicting formaldehyde nasal cancer risk in humans. The evidence of carcinogenicity of inhaled complex mixtures in experimental animals is very limited, while there is ample evidence that occupational exposure to mixtures such as wood, leather, or textile dust or chromium- and nickel-containing materials is associated with increased risk of nasal cancer. It is remarkable that these mixtures are aerosols, suggesting that their "particulate nature" may be a major factor in their potential to induce nasal cancer. Studies in rats have been conducted with defined mixtures of nasal irritants such as aldehydes, using a model for competitive agonism to predict the outcome of such mixed exposures. When exposure levels in a mixture of nasal cytotoxicants were equal to or below the "No-Observed-Adverse-Effect-Levels" (NOAELs) of the individual chemicals, neither additivity nor potentiation was found, indicating that the NOAEL of the "most risky chemical" in the mixture would also be the NOAEL of the mixture. In vitro models are increasingly being used to study mechanisms of nasal toxicity. However, considering the complexity of the nasal cavity and the many factors that contribute to nasal toxicity, it is unlikely that in vitro experiments ever will be substitutes for in vivo inhalation studies. It is widely recognized that a strategic approach should be available for the interpretation of nasal effects in experimental animals with regard to potential human health risk. Mapping of nasal lesions combined with airflow-driven dosimetry and knowledge about local metabolism is a solid basis for extrapolation of animal data to humans. However, more research is needed to better understand factors that determine the susceptibility of human and animal tissues to nasal toxicants, in particular nasal carcinogens.
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Affiliation(s)
- V J Feron
- Toxicology Division, TNO Nutrition and Food Research, Zeist, The Netherlands.
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Hosaka Y, Yanase H, Iwanaga T. Morphological analysis of olfactory receptor cells using whole-mount preparations of the rat nasal mucosa. J Vet Med Sci 1998; 60:897-904. [PMID: 9764401 DOI: 10.1292/jvms.60.897] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The distribution and entire shape of olfactory receptor cells were investigated by means of whole-mount preparations of the nasal mucosa. Whole mucosa isolated from the nasal septum of rats was processed, as "a free-floating section", and examined by the avidin-biotin complex (ABC) method using antisera against protein gene product 9.5 (PGP 9.5) and calbindin. Essentially all receptor cells were immunolabeled with the PGP 9.5 antiserum, but only half of PGP 9.5-immunoreactive cells were calbindin-immunoreactive. In the immunostaining of whole-mount preparations, pretreatment of tissues by freeze-thawing and dipping in ethanol and xylene greatly improved the permeability of antibodies. Overview of the nasal septum showed that the dorsal and ventral portions of the rostral olfactory area extended deeply into the respiratory area, making a "semi-lunar" shape. The boundary between the two areas was clearly demarcated, although several receptor cells were scattered in the respiratory area near the boundary. Observation at higher magnification clearly demonstrated that several axons derived from perikarya gathered to form nerve bundles showing a dendritic pattern. Proximal axons close to perikarya displayed beaded structures with intense immunoreactivity. They were electron-microscopically identified as swollen portions of axons which might be formed in association with the axonal flow. The present study showed that whole-mount preparation of the nasal mucosa for immunohistochemistry is a useful tool to analyze the morphology of olfactory receptor cells and axons.
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Affiliation(s)
- Y Hosaka
- Laboratory of Anatomy, Graduate School of Veterinary Medicine, Hokkaido University, Japan
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