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a b
M. Hayran
Fig. 32.11 The pseudostratied columnar epithelium (E)
of the respiratory region. (a) Light micrograph of the epidermis of the external nose (parafn block, stain: H&E)
and (b) light micrograph of the epidermis of the external
nose (Araldite block, stain: methylene blue) (scale bar:
and brush cells (Fig.32.11). All of these cells can
be investigated under TEM (Fig.32.12). However,
because some of these cells do not reach the surface of the epithelium, only three types (ciliated,
non-ciliated, and goblet cells) can be seen during
SEM studies (Fig.32.13).
The anterior one-third of the nasal cavity is
non-ciliated. Cilia begin just behind the front
edge of the inferior turbinate. The posterior part
of the nasal cavity, as well as the paranasal
sinuses, is densely covered by cilia [24]. However,
the epithelium on the tips of the nasal turbinates
is cuboidal and sparsely ciliated. Additionally,
mild squamous metaplasia may be seen around
these areas [16].
Ciliated columnar cells, the predominant cell
type at the surface, rest on the basement membrane and project both cilia and microvilli from
50μm). The specimens were obtained from fresh frozen
cadavers at a microscopic anatomy lab located at
Hacettepe University, Faculty of Medicine, Department of
Anatomy. H&E hematoxylin and eosin
Fig. 32.12 Electron micrograph respiratory epithelium
(TEM) (scale bar: 5 μm) (Araldite block, stain: uranyl
acetate/lead citrate). The specimen was obtained from a
fresh frozen cadaver at a microscopic anatomy lab at
Hacettepe University, Faculty of Medicine, Department of
Anatomy. TEM transmission electron microscopy. B basal
cell, C ciliated cell, G goblet cell, N non-ciliated cell
a
b
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c
429
d
Fig. 32.13 (a–d) Different areas on the nasal mucosal
surface. Electron micrograph of the respiratory epithelium
(SEM) (scale bar: 1μm). Surface invaginations of three
types of cells: ciliated (C), non-ciliated (N), and goblet
(G) cells. SEM scanning electron microscopy
their apical surface into the nasal lumen [23]
(Fig.32.14). Ciliated and non-ciliated columnar
cells interact with neighboring cells by tight
junctions and by interdigitations of the cell membrane. The cytoplasm contains many mitochondria located apically (Fig. 32.15), indicating a
highly active metabolism [24].
Each ciliated cell contains approximately
1000 motile cilia [23]. Cilia are hairlike extensions of the apical plasma membrane containing
an axoneme, a microtubule-based internal structure. Ultrastructurally, cilia are anchored to basal
bodies below the cell surface. The basal body is a
centriole-derived microtubule-organizing center
located in the apical region of the ciliated cell.
The basal body consists of nine short microtubule
triplets arranged in a ring. The basal bodies are
associated with several accessory structures (alar
sheets, basal feet, and striated rootlets) that
Fig. 32.14 Electron micrograph (TEM) of ciliated
columnar cells, the predominant cell type on the surface,
resting on the basement membrane and projecting both
cilia (C) and microvilli (M) from their apical surface
(scale bar: 1 μm) (Araldite block, stain: uranyl acetate/
lead citrate). The specimen was obtained from a fresh frozen cadaver at a microscopic anatomy lab at Hacettepe
University, Faculty of Medicine, Department of Anatomy.
TEM transmission electron microscopy
430
ab
B B
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Fig. 32.15 Electron micrograph (TEM) of the apical
cytoplasm of columnar cells with numerous mitochondria
(arrows) (scale bar: 500nm) (Araldite block, stain: uranyl
acetate/lead citrate). The specimen was obtained from a
fresh frozen cadaver at the microscopic anatomy lab at
Hacettepe University, Faculty of Medicine, Department of
Anatomy. TEM transmission electron microscopy
M. Hayran
anchor them in the cytoplasm. Axonemes are
formed by microtubules arranged in a characteristic “9+2” pattern. Nine outer pairs of microtubules make a cartwheel pattern at the periphery
of the axoneme, surrounding two single microtubules in the center (the inner microtubules)
(Fig.32.16). Each of the paired microtubules of
the ciliary axoneme is continuous with two of the
triplet microtubules of the basal body. When
examining a cross-section at high resolution,
each outer microtubule pair (doublet) can be seen
to be regularly arranged dynein arms (ciliary
dynein). Dynein is a microtubule-associated
motor protein. Each microtubule pair is linked to
adjacent pairs by an elastic substance called
nexin. Although the two central microtubules are
separate, they are partially enclosed by a central
sheath projection. Radial spokes extend from
each of the nine doublets toward the two central
microtubules [1, 23] (Fig.32.17).
A
Fig. 32.16 Diagram showing the basic structure of cilia
and electron micrographs of the cross (a) and longitudinal
(b) sections of the cilia (scale bar: 200nm). Line A and
M
M
B
line B indicate cross-section levels of the cilia, indicating
the cilia and the basal body, respectively. M microvilli
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431
Fig. 32.17 Cross-section of the cilia showing the organization of the axoneme (scale bar: 100nm), microtubule
pairs (doublet) (D), inner doublet (ID), outer dynein (OD)
arms (comprising ciliary dynein), and an elastic substance
All columnar cells, ciliated and non-ciliated,
are covered by microvilli, short and slender n-
gerlike cytoplasmic processes containing a core
of actin laments (Figs.32.13 and 32.18). They
are uniformly distributed over the entire apical
surface and increase the surface area of the epithelial cells, thus promoting exchange processes
across the epithelium [1]. The microvilli also prevent drying of the surface by retaining moisture
that is essential for ciliary function [24].
Another characteristic cell type of the airway
epithelium is the goblet cell (Fig. 32.19). The
moistening and protecting of the nasal mucosa by
secretion are mainly provided by mucous and
seromucous glands. However, goblet cells also
contribute to nasal secretion. The release mechanisms from goblet cells are not controlled by the
parasympathetic nervous system. It is considered
to be in response to physical and chemical irritants, but the mediators have not yet been clearly
identied. The surface epithelial cells are joined
by tight junctions, but ultrastructural studies have
called nexin (N). The two central microtubules (CM) are
separate; however, they are partially enclosed by a central
sheath projection. Radial spokes (RS) extend from each of
the nine doublets toward the two central microtubules
Fig. 32.18 Electron micrograph of a non-ciliated cell of
the respiratory epithelium (TEM) (scale bar: 500 nm).
TEM transmission electron microscopy, M microvillus
shown discontinuity of tight junctions around
lled goblet cells [24].
Basal cells are stem cells from which the other
cell types arise. They lie on the basement membrane and do not reach the lumen (Fig.32.12).
Small granule cells and cells that resemble basal
cells contain secretory granules.
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M. Hayran
a
b
Fig. 32.19 (a) Electron micrograph of the respiratory
epithelium (TEM) (scale bar: 2μm). Characteristic secretory cell called a goblet cell (G) and (b) Golgi complex
(arrow) (scale bar: 500nm) (Araldite block, stain: uranyl
Brush cells, a general name for those cells in
the respiratory tract, bear short, blunt microvilli.
The vomeronasal organ of Jacobson (VNO) is
the paired embryonic remnant that is situated
under the lower anterior side of the nasal septum.
It forms a tubular sac with a diameter of approximately 0.2–0.6 cm. Columnar epithelium with
microvilli on their apical surface lines this tubular structure. In many vertebrates, the VNO is
highly developed to establish intense olfactory
sensibility [13]. Differences in the frequency of
morphological patterns of the VNO between the
sexes may be one of the factors leading to variations in pheromone perception between men and
women [25, 26]. Even with a large number of literature on the human VNO, there is little
consensus on its persistence and functionality in
humans. While their precise function is unknown,
it is believed to be associated with pheromone
recognition and food avor perception [16,
26–28].
acetate/lead citrate). The specimen was obtained from a
fresh frozen cadaver at a microscopic anatomy lab at
Hacettepe University, Faculty of Medicine, Department of
Anatomy. TEM transmission electron microscopy
32.1.2.3 Olfactory Region
oftheNasal Cavity
The olfactory region is located on the roof of the
nasal cavity. Human olfaction is not as highly
developed as it is in other animals. In humans, the
olfactory region is formed by a modied pseudostratied epithelium occupying a small area.
The olfactory epithelium is composed of olfac-
tory receptor cells, supporting or sustentacular
cells, basal cells, and brush cells. In contrast with
the other regions of the nasal cavity, there are no
goblet cells in this segment.
Olfactory receptor cells are bipolar neurons
(Fig.32.20) that are spindle-shaped neurosensory
cells. At one end they have sensitive hairlike protrusions and nerve bers at the other end. They
have numerous microvilli and long slender cilia
on their apical surface. Olfactory receptor cells
have a single dendritic process-forming olfactory
vesicle. The cilia have typical basal bodies and
rise from the olfactory vesicle to the epithelial
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SC
ORC
EC
C
Fig. 32.20 Diagram of the olfactory epithelium. The
olfactory receptor cells (ORC) have specialized cilia (C),
supporting cells (sustentacular cell) (SC), and epithelial
columnar cells (brush cells) (EC) with large, blunt microvilli (M) on their apical surfaces
M
surface. The cilia are nonmotile or have limited
motility. The basal pole of the olfactory receptor
cell gives rise to unmyelinated axonal processes
that leave the epithelial compartment. They are
grouped into bundles and pass through the cribriform plate of the ethmoid bone to form the
olfactory bulb of the brain. Mitochondria and
smooth-surfaced endoplasmic reticula are abundant in their cytoplasm. They also possess lipofuscin granules, which cause the yellowish color
of human mucosa. Adherens junctions are present between these cells and the olfactory cells,
but the gap and tight junctions are absent [1].
Airborne chemicals diffuse across the mucous
membrane and reach the cilia, leading to stimulation of the olfactory receptor neuron. Each olfactory receptor makes a specic kind of olfactory
receptor protein. The receptors, when stimulated,
activate signaling cascades that eventually generate action potentials.
The other cell type in this mucosa is the sup-
porting cell (sustentacular cell). Their function is to
provide both metabolic and physical support to the
olfactory cells, similar to that of glial cells [1, 24].
The olfactory epithelium also contains a limited number of brush cells. As previously noted,
433
these cells are detected in the epithelium of the
other regions responsible for air passage conduction. They are columnar cells that exhibit large,
blunt microvilli at their apical surface, a feature
from which their name is derived. The basal surface of the brush cell makes synaptic contact with
nerve bers that penetrate the basal lamina. The
nerve bers are the terminal branches of the trigeminal nerve (cranial nerve V) that functions in
general sensation rather than olfaction. Brush
cells appear to be involved in the transduction of
general sensory stimulation of the mucosa [24].
Basal cells are the progenitors of the other
mature cell types. These are small rounded cells
located close to the basal lamina. Their nuclei are
frequently invaginated and lie at a level below
those of the olfactory cell nuclei. The cytoplasm
contains few organelles, a feature consistent with
their role as a reserve or stem cell. They proliferate and differentiate into supporting cells.
The lamina propria of the olfactory mucosa
is directly contiguous with the periosteum of the
underlying bone. This connective tissue contains numerous blood and lymphatic vessels,
unmyelinated olfactory nerves, myelinated
nerves, and olfactory glands (Bowman’s glands).
The olfactory glands, a characteristic feature of
the mucosa, are branched tubuloalveolar serous
glands that secrete via ducts to the olfactory surface. Lipofuscin granules are prevalent in gland
cells, and in combination with the lipofuscin
granules in the supporting cells of the olfactory
epithelium, they give the mucosa its natural
yellow- brown color. In the lamina propria, short
ducts composed of cuboidal cells lead away
from the glands. As the ducts pass through the
basal lamina into the olfactory epithelium, the
ductal cells become squamous and are then difcult to discern under light microscopy [24].
The serous secretion of the olfactory glands
serves as a trap and solvent for odoriferous substances. The constant ow from the glands rids
the mucosa of remnants of detected odoriferous
substances so that new scents can be continuously detected as they arise [24].
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M. Hayran
32.1.3 Clinical Orientation
oftheMicroscopic Anatomy
oftheNose
Examination of samples with electron microscopy is particularly aimed to evaluate alterations
and damages to the ultrastructural features of the
nose. Many diseases related to nasal structures are
the subject of electron microscopic studies,
including primary ciliary dyskinesia, allergic rhinopathy, and chronic inammatory hyperplasia.
Electron microscopy is also useful for the diagnosis in these cases. Ciliary impairment is the most
common cause of obstructive nasal diseases.
“Secretion” and “obstruction” are predominant
clinical symptoms in rhinology affecting patients
with disorders of the nose [18]. The surface characteristics of the cells should be investigated
under SEM in cases of ciliary dysfunction. TEM
studies are useful for many other diagnoses. For
many years, the cytological examination of nasal
secretions has been included among laboratory
diagnostic tests and performed with various methodologies (blowing, washing, or scraping).
However, the results obtained differ in terms of
their reliability and information. Using electron
microscopy, the study of the nasal mucosa can be
extended to the epithelial cytostructure with a
detailed depiction of even the thinnest ultrastructural components (cytoplasm and organelles,
cilia, and intercellular junctions) [29].
32.2 Conclusion
Electron microscopic investigation of the ultrastructural features of the nasal structures, especially nasal mucosal cells, provides important
information for both clinical diagnosis and
research. Nasal epithelial cells can be used as
indicators when the detailed investigation of the
epithelium is needed, not only for nasal structures but also for the whole air pathway. Epithelial
changes, inammation, or other pathological
conditions including mediator release and
receptor expression can be observed. In addition
to the biopsy materials, specimens can be estab-
lished from minimally invasive nasal brushings
[30]. Diagnosis for some undifferentiated neoplasms of the nose and nasal sinuses should also
be performed by electron microscopy.
Ultrastructural histopathology of human olfactory dysfunction can also be used for the classication and diagnosis of patients with olfactory
disorders.
Both clinicians and researchers can take
advantage of being aware of the benets of electron microscopy and the ultrastructural features
of the nose. This awareness offers new horizons
for future research and more advanced diagnoses
of patients.
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Genetic Background
https://t.me/medicina_free
oftheRhinologic Diseases
MehmetGunduz, EyyupUctepe, andEsraGunduz
33
Core Messages
• It is expected that the prevalence of allergic
rhinitis in the Western world will reach 50%
within the next 15years.
• Exposure early in childhood to microbes and
infections leads to modication of the immune
system, a reduced risk of IgE sensitization,
and a decreased risk of AR throughout life.
• People who have persistent nonallergic rhinitis based on the allergy skin test and serumspecic IgE test result might have a localized
form of allergic rhinitis.
• Information on the genetics of allergic diseases is valuable not only for analyzing the
molecular basis of allergic diseases but also
for investigating new drugs.
• Environmental effects on various genetic variants as well as epigenetics determine the fate
of chronic nasal diseases.
• CFTR genotype affects the progression of airway obstruction in CF.
• The studies demonstrated the role of various
modier genes such as ADIPOR2, EDNRA,
IFRD1, IL-8, MBL2, TCF7L2, MSRA,
SERPINA1, and TGF-b1in CF for patholo-
M. Gunduz (*) · E. Gunduz
Department of Otolaryngology Head and Neck
Surgery, Faculty of Medicine, Wakayama Medical
University, Wakayama, Japan
E. Uctepe
Acıbadem Labmed Ankara Tissue Typing Laboratory,
Ankara, Turkey
gies of pulmonary function, liver disease,
intestinal obstruction, diabetes, and infection.
• Variants in the promoter region (−509) and
rst exon (codon 10) of TGF-b1 are correlated
with poor lung function.
• ΔF508 homozygosity was associated with clinical severity of paranasal sinus diseases and
with the presence of polyps on endoscopy.
33.1 Introduction
Rhinologic diseases are very commonly seen
pathologies all over the world. They affect millions of people and cause huge social and economic burdens. In this chapter, the genetic origin
of the main rhinologic diseases is discussed.
These are allergic rhinitis, chronic sinusitis, vasomotor rhinitis, cystic brosis, and nasal polyps.
33.2 Architecture andFunction
oftheSinuses
The paranasal sinuses and turbinates are formed
from the primordial ridge during fetal development. Each sinonasal structure develops from
these ethmoturbinals separate from the inferior
turbinate. Although there is a fairly consistent
pattern to the formation of these structures,
resulting in a series of oblique structures that
attach to the ethmoid bulla, the extent and com-
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023
Ö. Ö. Celebi, T. M. Önerci (eds.), Nasal Physiology and Pathophysiology of Nasal Disorders,
https://doi.org/10.1007/978-3-031-12386-3_33
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plexity of pneumatization can be variable. There
is only the ethmoid sinus at birth, while the maxillary, frontal, and sphenoid sinuses are not fully
formed and expand out from these primary structures into their relevant cranial bones during
childhood and adolescence. Although the structure of the sinuses is well known, there are different opinions to explain the purpose and functions
of the paranasal sinuses. Among these, lightening
the weight burden of the cranium, adorning vocal
resonance, or constituting thermal insulation are
the most common ideas. Also, a recent theory
proposes that they form a “crumple zone” for the
crucial structures of the head such as the brain
and eyes to diminish damaging forces resulting
from sudden trauma [1].
It is shown that cranial sinuses produce nitric
oxide. This molecule has many functions in the
immune system such as killing microorganisms
(bacteria, viruses, and fungi) and tumor cells. So
the sinuses assist the innate immune defense of
the airway. Proper functioning of the sinuses
depends on sufcient drainage of their produced
mucus and normal ventilation. In this regulation,
mucociliary clearance is a highly coordinated
effort that consists of millions of beating cilia to
direct any mucus or particles toward the ostia of
the sinus. This process is quite prone to obstruction during swelling or inammation of the nasal
mucosa. Therefore, it causes a decrease in ciliary
beat frequency and results in poor drainage from
the sinus ostia [2]. This situation leads to stagnation of sinus secretions and a decrease in oxygen
level in the sinus, subsequently reducing mucociliary clearance and nitric oxide production.
33.3 Histopathologic Features
oftheNasal andSinus
Mucosa
The nasal mucosa is composed of a ciliated pseudostratied columnar epithelium which includes
ciliated and nonciliated columnar epithelial cells,
goblet cells, and basal cells [3, 4]. These cell
types lie on a basement membrane which includes
types I, III, and IV collagen brils; but, generally,
some of these cells cannot reach the luminal sur-
face and lead to the illusion of a stratied layer.
Just beneath the basement membrane is a cellfree zone, which includes bronectin and collagen types III and V and a submucosal layer
consisting of glands, inammatory and interstitial cells, extracellular matrix, nerves, and blood
vessels. There are three types of glands within
this layer: mucous, seromucous, and serous
glands. These glands, throughout epithelial goblet cells, synthesize the mucus that overlies the
epithelium and serve an antimicrobial function.
Furthermore, they transport particulate matter,
antigens, and bacteria by mucociliary clearance.
Serous glands synthesize secretory IgA, which is
essential in mucosal defense [5]. The submucosal
gland area constitutes almost 25% of the lamina
propria, while this ratio is only 15% in individuals without nasal allergies. Normally, lymphocytes, macrophages, and mast cells are the basic
cells in the nasal mucosa, and nasal mast cells are
usually found immediately beneath the basement
membrane.
33.4 Allergic Rhinitis andIts
Genetic Background
33.4.1 Introduction
Allergic rhinitis (AR) is a growing health and
social problem worldwide and the most common
type of chronic rhinitis. Most of the children with
AR become symptomatic and are diagnosed
before 6 years of age. Recent data indicate that
10–30% of adults and up to 40% of children in
developed countries suffer from this disease. The
prevalence of AR has increased considerably after
1950 in Western populations. Moreover, it is
thought that within the next 15years, the prevalence of allergic rhinitis in the Western world will
reach 50%. Almost 80% of all patients with AR
have symptoms before 20years of age. In some
patients, symptoms of AR can be detected before
2 years of age [6]. Current data suggest that
44–87% of patients with rhinitis might have mixed
rhinitis, both allergic and nonallergic types [7].
Environmental and lifestyle factors are impor-
tant in this prevalence increase. Because it is hard
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