oral mucous membrane - II.pptx

An Overview of Oral Mucous Membrane-II

• Parts of oral mucous
membrane
– Covering epithelium
– Underlying connective
tissue
– Submucosa
– Periosteum, muscle
• Three main types
– Masticatory mucosa
– Lining mucosa
– Specialized mucosa
courtesy :www.medscape.com/viewarticle/472915
•Two patterns of maturation
a) Keratinized
b) Non keratinized
Richard B. Presland, Ph.D.; Richard J. Jurevic, D.D.S.. Making Sense of the Epithelial Barrier:What Molecular Biology and
Genetics Tell Us About the Functions of Oral Mucosal and Epidermal Tissues. Journal of Dental Education April 2002.

Epithelial-Connective Tissue Interface
Basement membrane /Basal lamina
• Light microscope- 1-2µm thick is seen on the
lamina propria side of the junction
• Electron microscope- layer appears thinner

Basement membrane
Richard B. Presland, Ph.D.; Richard J. Jurevic, D.D.S.. Making Sense of the Epithelial Barrier:What Molecular Biology and
Genetics Tell Us About the Functions of Oral Mucosal and Epidermal Tissues. Journal of Dental Education April 2002.

• Using the electron microscope the following
layers of the basement membrane can be
distinguished:
Lamina rara externa - 10 to 50nm thick
Lamina densa -20 to 300nm, mostly 50 nm.
Lamina rara interna is only about 10 nm thick
Lamina fibroreticularis has a thickness of 200
- 500 nm. Rich in basotubules, 10 nm wide
microfibrillike structures.
Kimberley Brown. Epithelial Cells: Surface Domains & Junctions. Cell and Tissue Biology 2004

Structure of Hemidesmosome
Courtesy: xtal.cicancer.org/research.html

Protein Alternate terms Site
Keratin 5 Basal layer of stratified epithelia
Keratin 14 Basal layer of stratified epithelia
Plectin/HD1 Intracellular
IFAP300 Intracellular
P200 Intracellular
BPAg1 BP230 or dystonin Intracellular
BPAg2 BP180 or TYPE-XVII Transmembrane
collagen
a6b4 integrin Transmembrane
Laminin 5 Epiligrin or nicein or
kalinin BMZ
Laminin 6 BMZ
Ladinin LAD-1 BMZ
Uncein BMZ
Type-VII collagen BMZ
Type-IV collagen BMZ
Main hemidesmosome components
J Bagan, LL Muzio, C Scully.Mucosal Diseases Series.Number III.Mucous Membrane Pemphigoid.Oral diseases 2005;11:197-218

• Basement membrane (basal lamina) is a tough elastic structure
– Type IV and VII collagens
– heparan sulphate (HS) (perlecan)
– chondroitin sulphate (ChS)
– proteoglycans (versican), and
– glycoproteins
laminin
nidogen (entactin)
thrombospondin
tenascin
fibronectin
David F. Wilson et al. Oral cancer: Role of the basement membrane in invasion. Australian Dental Journal 1999;44:(2):93-97

Lamina lucida
• Glycoprotein layer
• It contains type IV
collagen
• It contains laminin and
entactin.
• Laminin and type IV
collagen promote
epithelial cell growth. Courtesy: www.ncbi.nlm.nih.gov/bookshelf/br.fcgi

• Laminins
– Laminin is a large, triple
chain molecule.
– α, β, γ subunits
• Integrins
– Family of transmembrane
proteins consisting of 2
subunits- α and β.
• Plectin and BP 230
– Members of the plakin
family
Courtesy: myworldatlarge.wordpress.com

Lamina densa
• Layer of finely
granular/filamentous
material that run
parallel to the basal cell
membranes of the
epithelial cells.
• Inserted into the lamina
densa are small loops of
finely banded fibrils
called anchoring fibrils.

REGIONAL VARIATIONS OF ORAL
MUCOSA

Lip
• Skin on its outer surface
• Labial mucosa on its inner
surface
• Vermilion zone/ Red zone/
Transitional zone
• Striated muscles in their core-
muscles of facial expression
• Minor mucous salivary glands
• Skin
– Keratinized layer of epidermis
on a bed of connective tissue
– Sweat glands, sebaceous glands
and bases of hair follicles
Section of skin of lip. A=keratinized epidermis,
B=shaft of hair, C=sebaceous gland, D=dermis.
Masson’s trichrome;x30
Fig.14.31
B.K.B.BERKOVITZ.ORAL ANTOMY, HISTOLOGY AND EMBRYOLOGY. FOURTH EDITION:MOSBY ELSEVIER;2009.CHAP.14;223-252.

Vermilion
• Lacks the appendages of skin
• Angles of the mouth-
sebaceous glands
• Constant moistening by the
tongue- lacks mucous glands
• Vermilion zone
– Epithelium is keratinized, thin
and translucent
– Connective tissue papilla are
long and narrow
• Intermediate zone- lacks a
granular layer and has a thick
parakeratinized layer
Section of red zone of lip. Keratinized epithelium
& lamina propria
H&E x80
Fig: 14.32

Labial Mucosa
• Thick, non keratinized
epithelium
• Lamina propria is wide
with short and irregular
papillae
• Sub mucosa- Minor
salivary glands Section of labial mucosa. A=non-keratinized oral
epithellium, B=lamina propria, C=minor salivary gland
in submucosa, D=fibres of orbicularis oris
H&E; x15
Fig: 14.33

Cheek
• Epithelium- non keratinized
• Lamina propria- dense with
short, irregular papillae
• Submucosa- minor mucous
salivary glands
• Linea alba- keratinized,
white line coincident with
the occlusal plane
• Fordyce’s spots- Sebaceous
glands appear as small
yellow patches
Section of buccal mucosa. B=non keratinized
oral epithelium, C=lamina propria, D=minor
salivary glands in submucosa, A=fibres of
buccinator muscle.
H&E;X15
Fig: 14.34

Alveolar Mucosa
• Thin, non keratinized
epithelium
• Lamina propria shows
poorly developed
dermal papillae
• Sub mucosa houses
many minor mucous
salivary glands
Section of lining oral epithelium from the alveolar
mucosa. Absence of keratin in the superficial
layer
H&E;x80
Fig: 14.13

Gingiva
• Two recognized regions
– Attached gingiva
– Free gingiva
– Gingival margin
– Gingival sulcus
• Mucogingival junction
Free gingival groove
courtesy :www.medscape.com/viewarticle/1893

Attached Gingiva
• Keratinized
• No sub mucosa
• Lamina propria-bound
directly to the bone
Crevicular(sulcular) epithelium
• Epithelium on the inner
surface of the gingiva
• Non keratinized
Section of parakeratinized oral epithelium from the
gingiva. The superficial layer stain more heavily for
keratin but nuclei are retained
H&E; x100
Fig: 14.12

Junctional epithelium
• Epithelial collar that surrounds the
tooth and extends from the region of
the cementum-enamel junction to
the bottom of the gingival crevice
• Two zones:
– A single layer of cuboidal cells- stratum
germinativum
– Several layers of flattened cells-
stratum spinosum
• Features of the junctional epithelium
– Hemidesmosomes and basal lamina-
Attachment apparatus/ Epithelial
attachment
– Internal basal lamina
– External basal lamina
Demineralized section showing the
dentogingival junction .A=region of attached
gingiva covered by masticatory epithelium,
B=region of free gingiva covered externally by
masticatory epithelium,C=non-keratinized
crevicular epithelium, D=non-keratinized
junctional epithelium
H&E; x30
Fig: 14.42

Cont…
Internal basal lamina- 2 zones
• Electron lucent zone adjacent to the cell
• Electron dense layer adjacent to the tooth
surface
• Lacks type IV collagen and anchoring fibrils
• Lamina propria
– Rich blood supply
• Turnover is rapid

Cont…
Enamel cuticle
• Non-mineralized structure interposed
between the junctional epithelium and the
underlying hard tissue
• Ultrastructurally
– Amorphous and biochemically distinct
– Proteinaceous and may be derived from serum

Gingival crevicular fluid
• Tissue fluid and cells passing through the
epithelium from the connective tissue- GCF
• Can be collected by capillary tubing, gingival
washing or absorbent paper strips
• Composition of GCF
– Immunoglobulins
– Complement
– Polymorphonucleocytes
– Epithelial squames

Interdental Gingiva
• Part of the gingiva
between adjacent teeth
• Wedge shaped
appearance
• Interdental col- curved
depression between the
buccal and lingual peaks
• Epithelium- non
keratinized and derived
from the reduced enamel
epithelium
Demineralized section of the interdental
papillae cut in the buccolingual plane
between two cheek teeth showing the
‘interdental col’.
H&E; x4
Fig: 14.53

Collagen fibres
• Type I collagen
• Functions
– Support of the free gingiva
– Binding of the attached gingiva to the alveolar
bone and tooth
– Linkage of one teeth to another

Types of Gingival Fibers
Diagram showing arrangement of
principal collagen fibre groups in
the lamina propria of the gingiva.
a.buccolingual section,
b.mesiodistal section, c.horizontal
section, d.buccolingual section
along the interdental col.
A= DENTOGINGIVAL FIBRES
B= LONGITUDINAL FIBRES
C= CIRCULAR FIBRES
D= ALVEOLO GINGIVAL FIBRES
E= DENTOPERIOSTEAL FIBRES
F= TRANSSEPTAL FIBRES
G= SEMICIRCULAR FIBRES
H= TRANSGINGIVAL FIBRES
I= INTERDENTAL FIBRES
J= VERTICAL FIBRES
Fig: 14.55
a
c
b d

Cont…
Lamina propria of gingiva
• Fibroblasts lack alkaline phosphatase
• Less contractile proteins
• Releases more prostaglandins
• Less ground substance and Type III collagen

Palate
Hard palate
• Keratinized and Para
keratinized epithelium
• Central region- no sub
mucosa
• Palate joins the alveolus-
sub mucosa contains
main neurovascular
bundles and minor
mucous salivary
glands(posteriorly) and
adipose tissue(anteriorly)
Demineralised section of the hard palate
showing the oral surface. A=lined by masticatory
epithelium and the nasal epithelium, B=lined by
a respiratory epithelium, C=bone of hard palate,
D=duct from mucous gland opening onto
surface
H&E;x110
Fig: 14.61

Cont…
• Nasal surface-
respiratory epithelium
– Ciliated columnar
epithelial cells and
goblet cells
– Vascular sub mucosa-
minor glands of both
mucous and serous
types
Section of nasal surface of hard palate. A=cilitated
columnar epithelium, B=goblet cell, C=minor gland
H&E;x500
Fig: 14.62

Soft Palate
• Non keratinized lining
mucosa
• Lamina propria
– Papilla are short and broad
– Elastic fibers and collagen
bundles are thin
• Sub mucosa
– Small mucous glands
– Attached to the palatal
muscles
• Nasal surface- respiratory
epithelium
Section of soft palate showing the oral surface being
covered by a non keratinized lining mucosa,
numerous minor salivary glands, palatal
musculature and nasal epithelium
H&E;x20
Fig: 14.63

Tongue and Floor of the Mouth
• Epithelium- thin, non
keratinized and shows short
papillae
• Sulcus terminalis
– Palatal surface
– Pharyngeal surface
• Anterior 2/3rd of tongue-
numerous papillae
– Filiform
– Fungiform
– Foliate
– Circumvallate
• Posterior 1/3rd of tongue
– Small lymphatic
nodules/follicles
Section showing the ventral surface of the
tongue(A), and floor of mouth(B) being lined by
non-keratinized lining epithelium
H&E;x20, fig: 14.64
Section of fungiform papillae on dorsal surface of
anterior part of tongue showing taste buds
H&E;x120, Fig: 14.68

• Anterior tongue
– Keratinized/ Para keratinized
epithelium
– Hair like tufts
• Filiform papillae
– Central core of lamina propria with
smaller, secondary papillae branching
from it
• Fungiform papillae
– Isolated, elevated mushroom-shaped
papillae scattered between the
filiform papillae
– 150-400µm in diameter
– Thin epithelium which is non-
keratinized
– Vascular core of lamina propria
– Taste buds may be found on the
surface
Section showing dorsum of anterior 2/3rd of
the tongue
H&E;x35
Fig: 14.66

• Foliate papillae
– One/ two longitudinal
clefts at the side of the
tongue
– Non keratinized epithelium
• Circumvallate papillae
– Large and rounded
– Surrounded by trench-like
feature
– Non keratinized epithelium
– Taste buds-internal wall of
the trench
– Small serous glands of von
Ebner
Section of circumvallate papillae, A=serous glands B=
of von Ebner empty via the ducts into the base of the
trench C= surrounding the papillae, which is not raised
above the surface of the tongue, D= muscle of tongue
H&E; x35
Fig: 14.72

Taste Buds
• Chemoreceptive organs-
Taste
• Located within the
epithelium
– Walls of the circumvallate
papillae
– Upper surface of fungiform
papillae
– Lateral walls of foliate
papillae
– Mucosa of the soft palate and
in the epiglottis
• 2 types of cells
– Supporting cell
– Taste cell
Section of wall of circumvallate papillae showing two
barrel-shaped areas representing two taste buds.
Masson’s trichrome; x300
Fig: 14.74

Cont…
• Taste cell- 4 distinct cell types
– Undifferentiated type IV cells
– Type I cells- dark appearance
– Type II and III cells- lighter
• Type I and III cells
– Form synapses with intragemmal nerves

Posterior tongue
• Collection of lymphoid
follicles- Lingual tonsil
• This forms a component
of Waldeyer’s ring-
protects the opening into
the pharynx
• Follicles are deep crypts
lined with epithelium and
containing a mass of
lymphoid material
• Follicles open onto the
surface of the tongue
• Contains small mucous
glands
Section of dorsal surface of posterior 1/3rd of
tongue containing a lymphoid follicle. This part
of the tongue is covered by a non keratinized
lining epithelium
H&E; x40, Fig: 14.76
Section of foliate papilla showing taste buds.
H&E; x200
Fig: 14.70

Functions of the oral mucosa
• It is protective mechanically against both compressive
and shearing forces
• It provides a barrier to microorganisms, toxins and
various antigens
• It has a role in immunological defense, both humoral
and cell mediated
• Minor glands within oral mucosa provide lubrication
and buffering as well as secretion of some antibodies.
The viscoelastic mucous film also acts as a barrier,
helping to retain water and electrolytes
• The mucosa is richly innervated, providing input for
touch, proprioception, pain and taste

• Keratinized epithelium
– Masticatory mucosa
• Gingiva
• Hard palate
– Vermilion border of the lip
• Non keratinized epithelium
– Lining mucosa
• Lip and cheek
• Vestibular fornix and alveolar
mucosa
• Inferior surface of tongue and
floor of oral cavity
• Soft palate
– Specialized mucosa
• Dorsal lingual mucosa
• Taste buds

References
• ANTONIO NANCI.TENCATE’S ORAL HISTOLOGY DEVELOPMENT, STRUCTURE
AND FUNCTION.SIXTH EDITION:ELSEVIER;2005.CHAP.12;329-375.
• B.K.B.BERKOVITZ.ORAL ANTOMY, HISTOLOGY AND EMBRYOLOGY. FOURTH
EDITION:MOSBY ELSEVIER;2009.CHAP.14;223-252.
• G S KUMAR.ORBAN’S ORAL HISTOLOGY AND EMBRYOLOGY.TWELFTH
EDITION:MOSBY ELSEVIER;2008. CHAP.9;210-257.
• David F. Wilson. Oral cancer: Role of the basement membrane in invasion.
Australian Dental Journal 1999;44:(2):93-97.
• Kimberley Brown. Epithelial Cells: Surface Domains & Junctions. Cell and
Tissue Biology 2004.
• J Bagan, LL Muzio, C Scully.Mucosal Diseases Series.Number III.Mucous
Membrane Pemphigoid.Oral diseases 2005;11:197-218.
• Geoffrey M.Cooper, Robert E.Hausman,editors.The Cell.A Molecular
Approach.Fourth Edition:ASM Press Washington D.C.;2007.Chap.14;569-575.

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