Bowman's Glands Research Articles

Molecular and Cellular Characterization of the Glutathione Transferases Involved in the Olfactory Metabolism of the Mammary Pheromone.

Odorant metabolizing enzymes, considered as critical olfactory perireceptor actors, control the odor molecules reaching the olfactory epithelium by biotransforming them. As an odorant, the mammary pheromone, i.e., 2-methylbut-2-enal (2MB2), emitted in the milk of lactating female rabbits triggers typical nipple searching-grasping behavior through orocephalic movements in newborn rabbits but not in weaned rabbits. We previously showed that 2MB2 perception is significantly modified when its glutathione transferase-dependent olfactory metabolism is affected in newborns. Here, enzymatic assays of the recombinant enzymes GSTA1, M1, and P1 revealed the activity of these enzymes toward the mammary pheromone. Histological experiments revealed strong expression of the GSTA class restricted to the Bowman glands and of GSTP1 in the nuclei of sustentacular cells. Moreover, some modulations of GSTs have been demonstrated, including a significant increase in GSTP1 expression (2-fold in mRNA, p value < 0.001; protein, p value: 0.031) after 45 min of mammary pheromone exposure at 10-2 g/mL and an increase in GSTA expression in weaned rabbits compared with newborn rabbits (3-fold in mRNA, p value: 0.011; protein, p value: 0.001). Our results provide new insights into the activity, cellular expression, and modulation of the mammary pheromone GST-metabolizing enzymes and clues about their olfactory function.

Comparative ultrastructure of the olfactory system in the East African root rat (Tachyoryctes splendens) and the naked mole rat (Heterocephalus glaber).

The ultrastructure of the olfactory system of most fossorial rodents remains largely unexplored. This study sought to investigate the functional structure of the olfactory mucosa and olfactory bulb of two species of fossorial rodents that have distinct behaviour and ecology, the East African root rat (RR) and the naked mole rat (NMR). Transmission electron microscopy and scanning electron microscopy were employed. The basic ultrastructural design of the olfactory system of the two species was largely comparable. In both species, the olfactory mucosa comprised an olfactory epithelium and an underlying lamina propria. The olfactory epithelium revealed olfactory knobs, cilia and microvilli apically and sustentancular cells, olfactory receptor neurons and basal cells in the upper, middle and basal zones, respectively. The lamina propria was constituted by Bowman's glands, olfactory nerve bundles and vasculature supported by loose connective tissue. Within the olfactory bulb, intracellular and extracellular structures including cell organelles, axons and dendrites were elucidated. Notable species differences were observed in the basal zone of the olfactory epithelium and on the luminal surface of the olfactory mucosa. The basal zone of the olfactory epithelium of the RR consisted of a single layer of flattened electron-dense horizontal basal cells while the NMR had juxtaposed electron-dense and electron-lucent heterogenous cells, an occurrence seen as being indicative of quiescent and highly proliferative states of the olfactory epithelia in the two species, respectively. The olfactory epithelial surface of the NMR comprised an elaborate cilia network that intertwined extensively forming loop-like structures whereas in the RR, the surface was rugged and consisted of finger-like processes and irregular masses. With gross and histological studies showing significant differences in the olfactory structures of the two species, these findings are a further manifestation that the olfactory system of the RR and the NMR have evolved differently to reflect their varied olfactory functional needs.

ACKR3 in olfactory glia cells shapes the immune defense of the olfactory mucosa.

Barrier-forming olfactory glia cells, termed sustentacular cells, play important roles for immune defense of the olfactory mucosa, for example as entry sites for SARS-CoV-2 and subsequent development of inflammation-induced smell loss. Here we demonstrate that sustentacular cells express ACKR3, a chemokine receptor that functions both as a scavenger of the chemokine CXCL12 and as an activator of alternative signaling pathways. Differential gene expression analysis of bulk RNA sequencing data obtained from WT and ACKR3 conditional knockout mice revealed upregulation of genes involved in immune defense. To map the regulated genes to the different cell types of the olfactory mucosa, we employed biocomputational methods utilizing a single-cell reference atlas. Transcriptome analysis, PCR and immunofluorescence identified up-regulation of NF-κB-related genes, known to amplify inflammatory signaling and to facilitate leukocyte transmigration, in the gliogenic lineage. Accordingly, we found a marked increase in leukocyte-expressed genes and confirmed leukocyte infiltration into the olfactory mucosa. In addition, lack of ACKR3 led to enhanced expression and secretion of early mediators of immune defense by Bowman's glands. As a result, the number of apoptotic cells in the epithelium was decreased. In conclusion, our research underlines the importance of sustentacular cells in immune defense of the olfactory mucosa. Moreover, it identifies ACKR3, a druggable G protein-coupled receptor, as a promising target for modulation of inflammation-associated anosmia.

Polycomb repressive complex 2 regulates basal cell fate during adult olfactory neurogenesis

Adult neurogenesis occurs in the mammalian olfactory epithelium to maintain populations of neurons that are vulnerable to injury yet essential for olfaction. Multipotent olfactory basal stem cells are activated by damage, although mechanisms regulating lineage decisions are not understood. Using mouse lesion models, we focused on defining the role of Polycomb repressive complexes (PRCs) in olfactory neurogenesis. PRC2 has a well-established role in developing tissues, orchestrating transcriptional programs via chromatin modification. PRC2 proteins are expressed in olfactory globose basal cells (GBCs) and nascent neurons. Conditional PRC2 loss perturbs lesion-induced neuron production, accompanied by altered histone modifications and misexpression of lineage-specific transcription factors in GBCs. De-repression of Sox9 in PRC2-mutant GBCs is accompanied by increased Bowman's gland production, defining an unrecognized role for PRC2 in regulating gland versus neuron cell fate. Our findings support a model for PRC2-dependent mechanisms promoting sensory neuronal differentiation in an adult neurogenic niche.

Predatory seduction: Scenting as a catalyst for power hierarchy in omegaverse fan fiction

This article expands on previous scholarship on the subject of social power in the Omegaverse fan fiction genre and how its often unequal distribution can be used as a metric for the various community perspectives on power. I examine how the wolfish trait of scenting (produced by extra olfactory glands) can be read to reinforce roles of predator and prey within the genre using examples from the popular Teen Wolf fandom. While some Omegaverse fics might use the animal traits, such as scenting, to manufacture predatory relationships for purposes beyond social commentary, there is overwhelming evidence in the more popular fics to support a more critical examination within the community of the power hierarchies they interact with.

Ablation of AQP5 gene in mice leads to olfactory dysfunction caused by hyposecretion of Bowman's gland.

Smell detection depends on nasal airflow, which can make absorption of odors to the olfactory epithelium by diffusion through the mucus layer. The odors then act on the chemo-sensitive epithelium of olfactory sensory neurons (OSNs). Therefore, any pathological changes in the olfactory area, for instance, dry nose caused by Sjögren's Syndrome (SS) may interfere with olfactory function. SS is an autoimmune disease in which aquaporin (AQP) 5 autoantibodies have been detected in the serum. However, the expression of AQP5 in olfactory mucosa and its function in olfaction is still unknown. Based on the study of the expression characteristics of AQP5 protein in the nasal mucosa, the olfaction dysfunction in AQP5 knockout (KO) mice was found by olfactory behavior analysis, which was accompanied by reduced secretion volume of Bowman's gland by using in vitro secretion measure system, and the change of acid mucin in nasal mucus layer was identified. By excluding the possibility that olfactory disturbance was caused by changes in OSNs, the result indicated that AQP5 contributes to olfactory functions by regulating the volume and composition of OE mucus layer, which is the medium for the dissolution of odor molecules. Our results indicate that AQP5 can affect the olfactory functions by regulating the water supply of BGs and the mucus layer upper the OE that can explain the olfactory loss in the patients of SS, and AQP5 KO mice might be used as an ideal model to study the olfactory dysfunction.

Effect of Cadmium Chloride Toxicity on Olfactory Mucosa

Cadmium is a highly toxic metal and affects the respiratory mucosa. The aim of the study is to show the inflammation and degenerative effect of cadmium on the olfactory mucosa. In this study, eight-week-old Wistar rats with an average weight of 170-190 g were divided into two groups (control and experiment) with 20 animals in each group and used in the experiments. The rats in the experimental group were given 2 mg/kg/day powdered cadmium chloride dissolved in water intraperitoneally every day for two weeks. At the end of the experiment, the nasal cavity was completely removed with anesthesia. Concha nasalis superior was separated, fixed with zinc-Formalin solution and decalcified with 5 % EDTA (Ethylene-diaminetetraacetic acid). After routine histopathological procedure, APAF-1 antibody was used for expression of Hematoxylin-Eosin (HE) and immunohistochemistry. Histopathological examination revealed interruptions in the basement membrane structure due to cadmium and degenerative changes in stem cells, degeneration in sensory cells and pycnosis in nuclei, dilatation in blood vessels and increased inflammation in connective tissue. APAF-1 expression was found to increase in epithelial cells and olfactory glands (Bowman gland) cells. It has been thought that cadmium toxicity increases cell degeneration and inflammation in the olfactory mucosa and may significantly affect cell death and olfactory metabolism by inducing the pro-apoptotic process.

Lipocalin 15 in the olfactory mucus is a biomarker for Bowman’s gland activity

Olfactory mucus contributes to the specific functions of the olfactory mucosa, but the composition and source of mucus proteins have not been fully elucidated. In this study, we used comprehensive proteome analysis and identified lipocalin 15 (LCN15), a human-specific lipocalin family protein, as an abundant component of the olfactory mucus. Western blot analysis and enzyme-linked immunosorbent assay (ELISA) using a newly generated anti-LCN15 antibody showed that LCN15 was concentrated in olfactory mucus samples, but not in respiratory mucus samples. Immunohistochemical staining using anti-LCN15 antibody revealed that LCN15 localized to the cytokeratin 18-positive Bowman's glands of the olfactory cleft mucosa. Quantitative image analysis revealed that the area of LCN15 immunoreactivity along the olfactory cleft mucosa significantly correlated with the area of neuron-specific Protein-Gene Product 9.5 (PGP9.5) immunoreactivity, suggesting that LCN15 is produced in non-degenerated areas of the olfactory neuroepithelium. ELISA demonstrated that the concentration of LCN15 in the mucus was lower in participants with normal olfaction (≥ 50 years) and also tended to be lower in patients with idiopathic olfactory loss (≥ 50 years) than in participants with normal olfaction (< 50 years). Thus, LCN15 may serve as a biomarker for the activity of the Bowman’s glands.

The Examination of Olfactory Function and Mucocilliary Transport in Gas Station Officers in Makassar, Indonesia

Introduction: Chronic exposure to fuel oil can cause chemical burns to the olfactory epithelium, which can cause anosmia. This study aimed to compare mucociliary transport time and olfactory function between operator and non-operator officers at gas stations. Methods: This cross-sectional study was conducted from September to November 2020 and involved 40 subjects divided into two equal groups each consisting of 20 gas station operators and non-operators, respectively. The examination of mucociliary transport time was carried out by saccharin test, while the olfactory function was examined by assessing e olfactory threshold, discrimination, and identification (TDI) score using the Sniffin sticks test. Results: There was a significant difference in the mean mucociliary transport time and olfactory function between gas station operators and non-operators (P&lt;0.001). In addition, there was also a significant correlation between the mucociliary transit time and olfactory function (p&lt;0.05), with a strong negative correlation coefficient (r=-0.620). Therefore, the longer the mucociliary transit time, the gas station attendant's olfactory function will decrease. Conclusion: mucociliary transport time and olfactory function in non-operator public gas station officers were better than operators, probably because inhalation of chemical pollutants induces the release of proinflammatory cytokines, chronic inflammation of the nasal mucosa results in impaired olfactory cells and mucin glands.

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.

Lectin histochemistry of the olfactory mucosa of Korean native cattle, Bos taurus coreanae.

The olfactory mucosa (OM) is crucial for odorant perception in the main olfactory system. The terminal carbohydrates of glycoconjugates influence chemoreception in the olfactory epithelium (OE). The histological characteristics and glycoconjugate composition of the OM of Korean native cattle (Hanwoo, Bos taurus coreae) were examined to characterize their morphology and possible functions during postnatal development. The OM of neonate and adult Korean native cattle was evaluated using histological, immunohistochemical, and lectin histochemical methods. Histologically, the OM in both neonates and adults consists of the olfactory epithelium and the lamina propria. Additionally, using periodic acid Schiff and Alcian blue (pH 2.5), the mucus specificity of the Bowman's gland duct and acini in the lamina propria was determined. Immunohistochemistry demonstrated that mature and immature olfactory sensory neurons of OEs express the olfactory marker protein and growth associated protein-43, respectively. Lectin histochemistry indicated that numerous glycoconjugates, including as N-acetylglucosamine, mannose, galactose, N-acetylgalactosamine, complex type N-glycan, and fucose groups, were expressed at varied levels in the different cell types in the OMs of neonates and adults at varying levels. According to our observations, the cattle possessed a well-developed olfactory system, and the expression patterns of glycoconjugates in neonatal and adult OMs varied considerably. This is the first study to describe the morphological assessment of the OM of Korean native cattle with a focus on lectin histochemistry. The findings suggest that glycoconjugates may play a role in olfactory chemoreception, and that their labeling properties may be closely related to OM development and maturity.

Морфологія нюхового аналізатора людини. Лекція

The sense of smell provides people with valuable information about the biochemical environment and their own body. Olfactory disorders occur in pathologies of the nasal cavity, liver cirrhosis, psychological and endocrine diseases. Smell affects various psychological aspects of people's lives, forming positive and negative emotional memories associated with smells. With the dysfunction of the olfactory analyzer, a person will not do the analysis whether the food is good, will not be able to feel the presence of poisonous gases in the air, bad breath. This puts a person in an awkward position and increases the risk of social isolation. The purpose of the study was to highlight the components of the normal structure and functioning of the human olfactory analyzer. Identification of odors in the environment and from one's own body is provided by the olfactory analyzer. Primary odors as camphor, floral, fruity, spicy, tarry, burnt and putrid in different quantities form secondary odors. Aromas are composed of volatile molecules called odorants. The smallest amount of odorant that causes an odor sensation is called the odor threshold. In people with coronavirus disease the sense of smell temporarily disappears (anosmia); it is reduced (hyposmia) in liver cirrhosis and rhinitis, and in Alzheimer's disease and schizophrenia besides hyposmia there is olfactory hallucination (phantosmia). Olfactory dysfunction adversely affects children's cognitive abilities. Fragrances change emotions and behavior. Aromas are used to regulate the physical and psychological state of the patient. Volatile molecules of fragrances penetrate through the layer of mucus that covers the olfactory epithelium located in the olfactory region of the nasal mucosa. The olfactory epithelium consists of olfactory, supportive and basal epitheliocytes, as well as secretory cells of the olfactory glands. Olfactory cells are modified nerve cells that have a body, an axon, and a dendrite, which ends with a receptor in the form of olfactory cilia. Volatile molecules interact with the olfactory cilia and then with the receptor protein, which is located on the olfactory cell bodies. In humans, olfactory cells have 350 receptor proteins. One type of receptor can register molecules of several different odorants. Molecules of the same odorant can activate several different receptors simultaneously. The nerve impulse from the olfactory cells (bodies of I neurons) reaches the nerve cells (bodies of II neurons) of the olfactory bulbs via their central outgrowths (olfactory filaments). Axons of nerve cells of olfactory bulbs continue to bodies of III neurons, which are located in subcortical centers of the brain (almond-shaped body, nuclei of the transparent septum). In human, to analyze a particular odor, axons from bodies of III neurons continue to cortex, namely to the area of the uncus of the parahippocampal gyrus

Enigmatic Neural Pathways: Potentiating Viral Neuroinvasion Into the CNS.

Enigmatic Neural Pathways: Potentiating Viral Neuroinvasion Into the CNS.

Epithelial morphometric alterations and mucosecretory responses in the nasal cavity of mice chronically exposed to hydrothermal emissions.

Air pollutants (either of natural or anthropogenic origin) represent a considerable environmental risk to human health by affecting the respiratory system and causing respiratory disorders. In this study, we investigate the effects of chronic exposure to hydrothermal emissions on the nasal cavity of mice since it is the first and the most exposed region of the respiratory system. This study, carried in S. Miguel Island, Azores-Portugal, used Mus musculus as a bioindicator species. Mice were captured in an area with non-eruptive active volcanism (Furnas Village) and another area without volcanism (Rabo de Peixe, reference site). The hydrothermal emissions present at Furnas Village are characterized by the continuous release of several gases (CO2, H2S, 222Rn) along with metals (e.g. Hg, Cd, Zn, Al) and particulate matter into the environment. We test the hypothesis whether chronic exposure to this specific type of pollution causes epithelial morphometric, mucosecretory and neuronal alterations on the nasal cavity. Thickness measurements were taken in the squamous, respiratory and olfactory epithelia. The relative density of cell types (basal, support and neurons) was also assessed in the olfactory epithelium and the mucosecretory activity was determined in the lateral nasal glands, Bowman's gland and goblet cells. Mice chronically exposed to hydrothermal emissions presented thinner olfactory epithelia and lesser mucous production, which could result in loss of olfactory capabilities as well as a decrease in the protective function provided by the mucous to the lower respiratory tract. For the first time, it is demonstrated that, in mice, this specific type of non-eruptive active volcanism causes epithelial and mucosecretory alterations, leading to the loss of olfactory capabilities.

X-Linked Hypohidrotic Ectodermal Dysplasia in Crossbred Beef Cattle Due to a Large Deletion in EDA.

Simple SummaryEctodermal dysplasias such as hypohidrotic ectodermal dysplasia (HED), are genetic conditions affecting the development and/or homeostasis of two or more ectodermal derivatives, including hair, teeth, nails, and eccrine glands. In particular, X-linked hypohidrotic ectodermal dysplasia-1 (ECTD1) in humans is characterized by a triad of signs comprising sparse hair, abnormal teeth, and anhidrosis or hypohidrosis. It has been reported in cattle, dogs, mice and rats. Until now, eight pathogenic variants in the bovine ectodysplasin A (EDA) gene causing ECTD1-like disorders have been found. Herein, five affected Red Angus-Simmental bull calves born over a 6-year period (2013–2019) in a single herd in the Western United States are reported showing an ECTD1-like syndrome. Calves were born with severe hypotrichosis and oligodontia. At age 1-week-old two calves died of severe pneumonia. Microscopic findings of the skin revealed small-caliber hair follicles with a mean density in flank skin slightly greater in affected animals than in control animals. Nasolabial, intranasal and tracheobronchial mucosal glands were absent, whereas olfactory glands were unaffected. Whole-genome sequencing (WGS) identified a 53 kb deletion of the X chromosome including parts of the EDA gene as well as the entire AWAT2 gene. The partial deletion of the EDA gene that is known to be associated with forms of ECTD1 is the most likely cause for the reported genodermatosis. Similar rare disorders in livestock are often not diagnosed at the molecular level due to lack of resources, short lifespan of the animals, and concerns for the producers’ reputation.X-linked hypohidrotic ectodermal dysplasia-1 (ECTD1) in people results in a spectrum of abnormalities, most importantly hypotrichosis, anodontia/oligodontia, and absent or defective ectodermally derived glands. Five Red Angus-Simmental calves born over a 6-year period demonstrated severe hypotrichosis and were diagnosed as affected with ECTD1-like syndrome. Two died of severe pneumonia within a week of birth. The skin of three affected calves revealed a predominance of histologically unremarkable small-caliber hair follicles. Larger follicles (>50 µm) containing medullated hairs (including guard and tactile hairs) were largely restricted to the muzzle, chin, tail, eyelids, tragus and distal portions of the limbs and tail. The mean histological density of hair follicles in flank skin of two affected calves was slightly greater than that in two unaffected calves. One affected calf was examined postmortem at 10 days of age to better characterize systemic lesions. Nasolabial, intranasal and tracheobronchial mucosal glands were absent, whereas olfactory glands were unaffected. Mandibular incisor teeth were absent. Premolar teeth were unerupted and widely spaced. Other than oligodontia, histological changes in teeth were modest, featuring multifocal disorganization of ameloblasts, new bone formation in dental alveoli, and small aggregates of osteodentin and cementum at the margins of the enamel organ. A 52,780 base pair deletion spanning six out of eight coding exons of EDA and all of AWAT2 was identified. Partial deletion of the EDA gene is the presumed basis for the reported X-chromosomal recessive inherited genodermatosis.

Značaj mirisa i ukusa u svakodnevnom životu - promene kod pacijenata sa COVID-19

Human-to-human transmission of coronavirus (SARS-CoV-2) - COVID-19 (corona virus disease 2019) - is characterized by a pandemic exponential rate and the patients with mild to moderate infection have odor and taste problems that represent a new atypical disease. A new viral syndrome of acute anosmia or "new loss of taste or smell" without rhinitis and nasal obstruction or rhinorrhea has been placed on the list of symptoms that may occur 2 to 14 days after exposure to the COVID-19 virus. Two months after declaring the COVID-19 pandemic in May 2020, the World Health Organization (WHO) has recognized changes in the perception of smell and taste as symptoms of this disease. The described cardinal symptoms are more common in the population of young patients and able-bodied people which facilitates the spread of disease. Significantly higher prevalence of patients with COVID-19 who have lost their taste and smell is treated at home (rare hospitalization), lung damage is rare, as well as oxygen therapy with mild lymphopenia. Different scenarios of SARS-CoV-2 viral infection can be assumed: it is probable that the virus does not enter directly into olfactory sensory neurons (they do not have ACE2 and TMPRSS2 receptors), but it is localized to vascular pericytes and causes inflammatory processes and vasculopathies. On the other hand, direct infection of non-neuronal cells which contain said receptors is possible. Those are specific cell types in the olfactory epithelium such as sustentacular, horizontal basal cells, as well as Bowman's glands, which leads to massive degeneration and loss of olfactory neurons. The sense of taste is a complex sensation that is the result of the interaction of smell, taste, temperature and texture of food. The virus damages cranial nerves, epithelial receptors and blood vessels leading to taste damage (ageusia or dysgeusia). A multidisciplinary approach with epidemiological, clinical and basic research is needed to elucidate the mechanism of sensorineural odor and taste loss caused by coronavirus.

Exploring Pleiotropic Functions of Canine β-Defensin 103: Nasal Cavity Expression, Antimicrobial Activity, and Melanocortin Receptor Activity.

Canine β-defensin 103 (cBD103) and its common variant cBD103ΔG23 are multitasking polypeptides. As a β-defensin, cBD103 is one of many antimicrobial agents used by the innate immunity to thwart pathogenic colonization. In this study, we showed that cBD103 was expressed throughout the nasal cavity, with primary expression in the nares as well as respiratory and olfactory epithelia. In the rostral nasal concha, cBD103 was expressed in the epithelium, and to a lesser degree in the lamina propria, but was absent in goblet cells. In the main olfactory epithelium, virtually all cells in the epithelial layer and select cells associated with Bowman's glands expressed cBD103. We also showed that the ΔG23 mutation did not appreciably alter the antimicrobial activity of the peptide against several species of microorganisms tested in nutrient-rich or minimal media or minimal media with salt added. Moreover, we showed antimicrobial activity in minimal media did not necessarily predict the inhibitory action of the peptide in nutrient-rich media. Both forms of cBD103 caused ultrastructural changes (membrane blebbing, condensation of intracellular contents and cell wall lysis) in Escherichia coli and Staphylococcus aureus. As a ligand of the melanocortin receptors, we showed that cBD103ΔG23 increased ERK1/2 activation and cAMP accumulation when bound to the human or canine melanocortin-4 receptor, acting as a weak allosteric agonist.

Ultrastructure and Development of the Olfactory Organ in Indigenous Pelophylax Ridibundus (Amphibia, Rana)

Two olfactory placodes were formed in early embryonic stages. The olfactory epithelia contain receptor, supporting and basal cells. Receptor cells are represented by elongated ciliated cells or microvillated cells, most of the supporting cells are ciliated and some of them are secretory cells. The olfactory placode developed into a principal cavity that differentiated into three chambers as ciliated supporting cells, secretory supporting cells and abundance of ciliated receptor cells and microvillated cells. We observed a tiny projections of small secretory supporting cells of the principle cavity, arranged in row, known as Bowman’s glands to detect odorants in the air, together with the surrounding supporting cells are presumply responsible for mucus-coating the epithelium of the principle cavity.

Muc5b is mainly expressed and sialylated in the nasal olfactory epithelium whereas Muc5ac is exclusively expressed and fucosylated in the nasal respiratory epithelium.

The nose is a complex organ that filters and warms breathing airflow. The nasal epithelium is the first barrier between the host and the external environment and is covered by a mucus gel that is poorly documented. Mucins are large, heavily O-glycosylated polymeric molecules secreted in the nose lumen by specialized cells, and they are responsible for the biochemical properties of the mucus gel. The mucus traps particles and clears them, and it also bathes microbiota, host molecules, and receptors that are all essential for odor perception in the olfactory epithelium. We used histology and immunohistochemistry to study the expression of the two main airway polymeric mucins, Muc5ac and Muc5b, in wild-type, green fluorescent protein-reporter Muc5b, and in genetically Muc5b-deficient mice. We report that Muc5ac is produced by goblet cells at the cell surface in the respiratory epithelium but is not expressed in the olfactory epithelium, whereas Muc5b is secreted by Bowman's glands situated in the lamina propria beneath the olfactory epithelium and also by goblet cells in the distal part of the respiratory epithelium. We also observed that Muc5b-deficient mice exhibited depletion of Bowman's glands. Using lectins, we found that terminally O-glycosylated chains of Muc5b were sialylated but not fucosylated, whereas Muc5ac was fucosylated but not sialylated. Specific localization and specific terminal glycosylation of the two mucins suggest different functions of the mucins.

Possible ATP trafficking by ATP‐shuttles in the olfactory cilia and glucose transfer across the olfactory mucosa

Odor transduction in the cilia of olfactory sensory neurons involves several ATP-requiring enzymes. ATP is generated by glycolysis in the ciliary lumen, using glucose incorporated from surrounding mucus, and by oxidative phosphorylation in the dendrite. During prolonged stimulation, the cilia maintain ATP levels along their length, by unknown means. We used immunochemistry, RT-PCR, and immunoblotting to explore possible underlying mechanisms. We found the ATP-shuttles, adenylate and creatine kinases, capable of equilibrating ATP. We also investigated how glucose delivered by blood vessels in the olfactory mucosa reaches the mucus. We detected, in sustentacular and Bowman's gland cells, the crucial enzyme in glucose secretion glucose-6-phosphatase, implicating both cell types as putative glucose pathways. We propose a model accounting for both processes.