Morphology of the Human Olfactory Analyzer

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

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The Development of Olfactory Organ of Lissotriton Vulgaris (Amphibia, Caudata)

Vestnik Zoologii ◽

10.1515/vzoo-2015-0066 ◽

2015 ◽

Vol 49 (6) ◽

pp. 559-566 ◽

Cited By ~ 4

Author(s):

M. F. Kovtun ◽

Ya. V. Stepanyuk

Keyword(s):

Nasal Cavity ◽

Olfactory Epithelium ◽

Vomeronasal Organ ◽

Developmental Period ◽

Olfactory Organ ◽

Peripheral Part ◽

Lissotriton Vulgaris ◽

Olfactory Analyzer ◽

Gland Development ◽

Olfactory Pit

Abstract The Development of Olfactory Organ of Lissotriton vulgaris (Amphibia, Caudata). Kovtun, M. F, Stepanyuk, Ya. V. - Using common histological methods, the morphogenesis of olfactory analyzer peripheral part of Lissotriton vulgaris (Amphibia, Caudata) was studied, during the developmental period starting with olfactory pit laying and finishing with definitive olfactory organ formation. Special attention is paid to vomeronasal organ and vomeronasal gland development. Reasoning from obtained data, we consider that vomeronasal organ emerged as the result of olfactory epithelium and nasal cavity differentiation.

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MODERN CONCEPTION AS TO THE FUNCTIONAL MORPHOLOGY OF THE OLFACTORY SYSTEM AND ITS CHANGES UNDER THE INFLUENCE OF SOME EXOGENOUS POLLUTANTS

The Medical and Ecological Problems ◽

10.31718/mep.2019.23.3-4.09 ◽

2019 ◽

Vol 23 (3-4) ◽

pp. 37-40

Author(s):

A.D. Shkodina ◽

R.M. Hrinko ◽

I.I. Starchenko

Keyword(s):

Environmental Factors ◽

Olfactory Epithelium ◽

Functional Organization ◽

Morphological Changes ◽

Human Life ◽

Experimental Studies ◽

Experimental Models ◽

Functional Changes ◽

Olfactory Analyzer ◽

Long Time

The interaction between a body and an environment provides the main aspects of human life. The study of the functional structure of the olfactory analyzer plays an important role both in clinical and in experimental studies, but the question of its features in humans needs detailed research. The paper presents the modern data of the structural and functional organization of the olfactory analyzer. Particular attention is paid to the structural organization of olfactory bulbs as most complicated and least studied component of the olfactory analyzer. The morphological and functional changes of the olfactory analyzer are developing in some diseases and in action of adverse environmental factors are described while the accentuation is placed on the differences of the mechanism in the pathogenesis of damage to the olfactory analyzer, depending on the nature of the influence of pathogenic factors. In this way as the result of short-term intense effects of the pollutant, irreversible atrophic changes are primarily affected to the olfactory epithelium, thus, to some extent, preventing the spread of the toxin to other analyzer structures. Conversely, a long-term exposure to low doses usually retains the functional activity of the olfactory epithelium, while harmful substances penetrate the central unit of the olfactory analyzer. In such cases, the olfactory dysfunction can be diagnosed after a long time after the start of the cohort with certain pollutants. Currently, studies of the influence of exogenous toxins on various parts of the olfactory analyzer on animal experimental models are quite active. At the same time, the issue of functional and morphological changes in various structural components of the human olfactory analyzer under the influence of negative environmental factors remains poorly understood and requires further morphological and biochemical studies, in order to be able to further develop effective therapeutic and prophylactic means.

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Enhancement of the Olfactory Response by Lipocalin Cp-Lip1 in Newt Olfactory Receptor Cells: An Electrophysiological Study

Chemical Senses ◽

10.1093/chemse/bjz048 ◽

2019 ◽

Vol 44 (7) ◽

pp. 523-533

Author(s):

Tadashi Nakamura ◽

Yoshihiro Noumi ◽

Hiroyuki Yamakawa ◽

Atsushi Nakamura ◽

Durige Wen ◽

...

Keyword(s):

Olfactory Epithelium ◽

Olfactory Receptor ◽

Electrophysiological Study ◽

Dependent Manner ◽

Impulse Frequency ◽

Concentration Dependent Manner ◽

Olfactory Receptor Cells ◽

Receptor Cells ◽

Electrophysiological Responses ◽

Olfactory Cells

Abstract Previously, we have detected the expression of 2 lipocalin genes (lp1 and lp2) in the olfactory epithelium of the Japanese newt Cynops pyrrhogaster. Recombinant proteins of these genes (Cp-Lip1 and Cp-Lip2, respectively) exhibited high affinities to various odorants, suggesting that they work like the odorant-binding proteins (OBPs). However, the physiological functions of OBP generally remain inconclusive. Here, we examined the effect of Cp-Lip1 on the electrophysiological responses of newt olfactory receptor cells. We observed that the electro-olfactogram induced by the vapor of an odorant with high affinity to Cp-Lip1 appeared to increase in amplitude when a tiny drop of Cp-Lip1 solution was dispersed over the olfactory epithelium. However, the analysis was difficult because of possible interference by intrinsic components in the nasal mucus. We subsequently adopted a mucus-free condition by using suction electrode recordings from isolated olfactory cells, in which impulses were generated by puffs of odorant solution. When various concentration (0–5 µM) of Cp-Lip1 was mixed with the stimulus solution of odorants highly affinitive to Cp-Lip1, the impulse frequency increased in a concentration-dependent manner. The increase by Cp-Lip1 was seen more evidently at lower concentration ranges of stimulus odorants. These results strongly suggest that Cp-Lip1 broadens the sensitivity of the olfactory cells toward the lower concentration of odorants, by which animals can detect very low concentration of odorants.

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Mosaic cellular patterning in the nose: Adhesion molecules give their two scents

The Journal of Cell Biology ◽

10.1083/jcb.201602023 ◽

2016 ◽

Vol 212 (5) ◽

pp. 495-497 ◽

Cited By ~ 1

Author(s):

Gerard M.J. Beaudoin

Keyword(s):

Differential Expression ◽

Adhesion Molecules ◽

Olfactory Epithelium ◽

Sensory Cells ◽

Supporting Cells ◽

Mosaic Pattern ◽

Sense Of Smell ◽

Cell Biol ◽

Cellular Patterning

The sense of smell is mediated by the olfactory epithelium, which is composed of a mosaic pattern of olfactory sensory cells surrounded by supporting cells. In this issue, Katsunuma et al. (2016. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201509020) show that the differential expression of nectins and cadherins establishes this pattern.

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A comparison of the number of nerve cells in the olfactory bulbs of domesticated albino and wild Norway rats

The Journal of Comparative Neurology ◽

10.1002/cne.900450204 ◽

1928 ◽

Vol 45 (2) ◽

pp. 483-501 ◽

Cited By ~ 14

Author(s):

Leslie A. Smith

Keyword(s):

Nerve Cells ◽

Olfactory Bulbs ◽

Norway Rats

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In goldfish the discriminative ability for odours persists after reduction of the olfactory epithelium, and rapidly returns after olfactory nerve axotomy and crossing bulbs

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2000.0671 ◽

2000 ◽

Vol 355 (1401) ◽

pp. 1219-1223 ◽

Cited By ~ 1

Author(s):

Hans Peter Zippel

Keyword(s):

Amino Acid ◽

Olfactory Epithelium ◽

Functional Recovery ◽

Olfactory System ◽

Olfactory Nerve ◽

Sensory Cells ◽

Similar Concentration ◽

Olfactory Bulbs ◽

Discriminative Ability ◽

Bilateral Lesions

Goldfish are ideal vertebrates for the study of regeneration within the peripheral and the central olfactory system. The present behavioural investigations studied the effects of bilateral lesions on the animals' ability to qualitatively discriminate two amino acids (107 -6 M) and their performance in two more difficult tasks: (i) rewarded amino acid applied in a lower concentration, and (ii) rewarded stimulus contaminated. A 50 and 85% reduction of the olfactory epithelium resulted in no recordable behavioural deficit. After axotomy of olfactory nerves and lateral olfactory tractotomy, fishes were anosmic for seven to ten days. Following replacement of sensory cells in the epithelium, and after regeneration of olfactory tract fibres a full functional recovery, i.e. a highly specific regeneration, was recorded. After three surgical modifications of the olfactory bulbs' position, (i) crossing olfactory tracts and bulbs, (ii) crossing tracts and turning bulbs, and (iii) turning bulbs upside down, a full functional recovery was recorded for amino-acid discrimination in a similar concentration. A permanent, and similar slight deficit was, however, found during application of different concentrations, and of contaminated stimuli when medial lateral halves of the bulb were in ‘incorrect’ position (i) and (iii), or olfactory bulbs were positioned in the vicinity of the contralateral epithelium (i) and (ii).

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Synergistic action of nectins and cadherins generates the mosaic cellular pattern of the olfactory epithelium

The Journal of Cell Biology ◽

10.1083/jcb.201509020 ◽

2016 ◽

Vol 212 (5) ◽

pp. 561-575 ◽

Cited By ~ 22

Author(s):

Sayaka Katsunuma ◽

Hisao Honda ◽

Tomoyasu Shinoda ◽

Yukitaka Ishimoto ◽

Takaki Miyata ◽

...

Keyword(s):

Olfactory Epithelium ◽

Synergistic Action ◽

Supporting Cells ◽

Mosaic Pattern ◽

Cell Systems ◽

Single Mechanism ◽

Cellular Pattern ◽

Model Cell ◽

Olfactory Cells ◽

Combinatorial Expression

In the olfactory epithelium (OE), olfactory cells (OCs) and supporting cells (SCs), which express different cadherins, are arranged in a characteristic mosaic pattern in which OCs are enclosed by SCs. However, the mechanism underlying this cellular patterning is unclear. Here, we show that the cellular pattern of the OE is established by cellular rearrangements during development. In the OE, OCs express nectin-2 and N-cadherin, and SCs express nectin-2, nectin-3, E-cadherin, and N-cadherin. Heterophilic trans-interaction between nectin-2 on OCs and nectin-3 on SCs preferentially recruits cadherin via α-catenin to heterotypic junctions, and the differential distributions of cadherins between junctions promote cellular intercalations, resulting in the formation of the mosaic pattern. These observations are confirmed by model cell systems, and various cellular patterns are generated by the combinatorial expression of nectins and cadherins. Collectively, the synergistic action of nectins and cadherins generates mosaic pattern, which cannot be achieved by a single mechanism.

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Proprotein convertase subtilisin/kexin type 9 (PCSK9) levels are not associated with severity of liver disease and are inversely related to cholesterol in a cohort of thirty eight patients with liver cirrhosis

Lipids in Health and Disease ◽

10.1186/s12944-021-01431-x ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Susanne Feder ◽

Reiner Wiest ◽

Thomas S. Weiss ◽

Charalampos Aslanidis ◽

Doris Schacherer ◽

...

Keyword(s):

Liver Cirrhosis ◽

Liver Disease ◽

Cholesteryl Ester ◽

Hepatic Vein ◽

Cholesterol Metabolism ◽

Ldl Receptor ◽

Receptor Protein ◽

Proprotein Convertase ◽

Protein Levels ◽

Systemic Vein

Abstract Background Proprotein convertase subtilisin/kexin type 9 (PCSK9) is of particular importance in cholesterol metabolism with high levels contributing to hypercholesterolemia. Cholesterol and sphingolipids are low in patients with liver cirrhosis. Purpose of this study was to find associations of plasma PCSK9 with circulating cholesterol and sphingolipid species and measures of liver disease severity in patients with liver cirrhosis. Methods PCSK9 protein levels were determined by ELISA in systemic vein (SVP), hepatic vein (HVP) and portal vein plasma of patients with mostly alcoholic liver cirrhosis. PCSK9 and LDL-receptor protein expression were analysed in cirrhotic and non-cirrhotic liver tissues. Results Serum PCSK9 was reduced in patients with liver cirrhosis in comparison to non-cirrhotic patients. In liver cirrhosis, plasma PCSK9 was not correlated with Child-Pugh score, Model for End-Stage Liver Disease score, bilirubin or aminotransferases. A negative association of SVP PCSK9 with albumin existed. PCSK9 protein in the liver did not change with fibrosis stage and was even positively correlated with LDL-receptor protein levels. Ascites volume and variceal size were not related to PCSK9 levels. Along the same line, transjugular intrahepatic shunt to lower portal pressure did not affect PCSK9 concentrations in the three blood compartments. Serum cholesterol, sphingomyelin and ceramide levels did not correlate with PCSK9. Stratifying patients by high versus low PCSK9 levels using the median as cut-off, several cholesteryl ester species were even low in the subgroup with high PCSK9 levels. A few sphingomyelin species were also reduced in the patients with PCSK9 levels above the median. PCSK9 is highly expressed in the liver but systemic, portal and hepatic vein levels were similar. PCSK9 was not correlated with the inflammatory proteins C-reactive protein, IL-6, galectin-3, resistin or pentraxin 3. Of note, HVP PCSK9 was positively associated with HVP chemerin and negatively with HVP adiponectin levels. Conclusions In the cohort of patients with liver cirrhosis mostly secondary to alcohol consumption high PCSK9 was associated with low levels of certain cholesteryl ester and sphingomyelin species. Positive correlations of PCSK9 and LDL-receptor protein in the liver of patients with chronic liver injury are consistent with these findings.

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Chemoreception and the sense of smell

Sensory Transduction ◽

10.1093/oso/9780198835028.003.0007 ◽

2019 ◽

pp. 132-158

Author(s):

Gordon L. Fain

Keyword(s):

Olfactory Epithelium ◽

Olfactory Receptor ◽

Olfactory System ◽

Vomeronasal Organ ◽

Sensory Transduction ◽

General Description ◽

Receptor Proteins ◽

Sense Of Smell ◽

Anatomy And Physiology ◽

Accessory Olfactory System

“Chemoreception and the sense of smell” is the seventh chapter of the book Sensory Transduction and begins with a general description of chemoreception, including chemotaxis in bacteria. It then describes olfaction in insects, including new discoveries of the nature of insect receptor proteins and the coding of olfaction in insects. It proceeds to review olfaction in vertebrates, beginning with the primary olfactory epithelium. It describes olfactory receptor proteins, the mechanism of olfactory transduction, and pathways of desensitization and adaptation. The basis of coding in the principal olfactory epithelium is described together with the anatomy and physiology of the olfactory bulb. A final section is provided on the accessory olfactory system and vomeronasal organ, including a description of receptor proteins, transduction cascades, and wiring to the accessory olfactory bulbs.

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