HISTOLOGY OF ORAL MUCOUS MEMBRANE & IT’S CLINICAL

IMPLICATION

Dr. Sudeep M Chaudhari

1st year PG
Dept of Pedodontics & Preventive Dentistry
 Contents
 Introduction
 Classification
 Function
 Structure of oral mucosa
A) Epithelium
I) Keratinized epithelium
1) Stratum basale
2) Stratum spinosum
3) Stratum granulosum
4) Stratum corneum
II)Non keratinized epithelium
Difference between keratinized & non-
keratinized epithelium
B) Lamina propria
C) Submucosa
 Subdivisions of oral mucosa
I. Masticatory mucosa
II. Lining mucosa
III.Specialized mucosa
 Clinical considerations

Introduction
  Body cavities that communicate with the external surface are lined by
mucous membranes, which are coated by serous and mucous secretions.
 The surface of the oral cavity is a mucous membrane. The oral mucosa
is continuous with the skin of the lip through the vermilion
border.Posteriorly it is continuous with the mucosa of the pharynx.
 Its structure varies in an apparent adaptation to function in different
regions of the oral cavity.

Classification

Based upon primary function served :-

1.Masticatory mucosa (gingiva and hard palate)
2. Lining or reflecting mucosa (lip, cheek, vestibular fornix, alveolar
mucosa, floor of mouth and soft palate)
3.Specialized mucosa (dorsum of the tongue and taste buds)

Based upon keratinisation

 1. Keratinised
-Orthokeratinized
-Parakeratinized
2. Non-keratinised.

Based upon Location

1. Buccal Mucosa.
2. Lingual Mucosa.
3. Palatal Mucosa.
4. Labial Mucosa.
5. Alveolar Mucosa.

Function
(1) Defense-
 Integrity of the oral epithelium is an effective barrier for the entry
of the micro-organisms.
 Oral cavity contains wide variety of micro-organisms
 Oral mucosa is impermeable to bacterial toxins.
(2) Lubrication-
 Secretion of salivary glands keeps the oral cavity moist
 A moist oral cavity helps in speech, mastication, swallowing &
perception of taste
(3) Sensation-
 Temperature (heat and cold), touch, pain
 Reflexes such as swallowing, gagging and salivation
(4) Protection-
 Oral mucosa protect deeper tissues from masticatory forces &
from abrasive nature of foodstuff

Structure Of Oral Mucosa

 A)
B) EpitheliumLamina Propria
C)Submucosa

A)Oral Epithelium
Epithelium of the oral mucosa is stratified squamous epithelium
May be – I)keratinized
 orthokeratinized
 parakeratinized
– II)nonkeratinized
Cytokeratin forms the cytoskeleton of all epithelial cells, along with
microfilaments & microfibrils

Cytokeratin seen not only in cell but also in cell contact area like
desmosomes

It provides mechanical linkages & distribute the forces over the wide
area

I)Keratinized Epithelium
Has keratinocytes arranged in four cell layers
1) Stratum basale 2) Stratum spinosum
3) Stratum granulosum 4) Stratum corneum


A single cell is, at different time,a part of each layer
 
After mitosis, it may remain in thebasal layer & divide again or it
may
pushed upward
 During migration – biochechemical
& morphological changes occurs –
this is termed as differentiation
 Differentiation ends with the
formation of a keratinized squama
 After reaching the surface it is
shed off, this process called as
desquamation
 The process of cell migration from
basal layer to the surface – maturation
 The time taken for cell divide & pass through the
entire epithelium – turnover time
• Skin : 52 – 75 days
• Gut : 4 – 14 days
• Gingiva : 41 – 57 days
• Cheek : 25 days
• Junctional Epithelium : 5 - 6 days

1)Stratum basale
Made up of single layer of cuboidal cells
➔ Synthesize DNA & undergoes mitosis
➔ Shows ribosomes & elements of rough endoplasmic reticulum –
indicative of protein synthesis
➔ Proteins of basal lamina & proteins which form the intermediate
filaments of the basal lamina

2)Stratum spinosum
➔Made up of polyhedral cells which are larger than basal cells
➔ Cells are joined by intercellular bridges
➔ These cells are most active in protein synthesis
➔

3) Stratum granulosum
➔Contains flatter & wider cells which are larger than spinous cells
➔ Contains basophilic keratohyalin granules
➔ Nuclei shows sign of degeneration & pyknosis
➔ Still synthesizes protein
➔ Cell surface become more regular
➔ The lamellar granule – a small organelle (keratinosomes / Odland
body / membrane coating granule) forms – these granules discharge
their contents into the intercellular space forming an intercellular
lamillar material – which contributes to the permeability barrier

4) Stratum corneum
➔Madeup of acidophilic keratinized squamae, which is larger & flatter
than the granular cell layer
➔ Thickness of this layer varies at different sites in the oral cavity
➔ Here all of the nuclei & other organelles have disappeared

Types of keratinized epithelium

➔ Parakeratinized Epithelium :The superficial cells are dead but retain
the nucleus
➔ Orthokeratinized Epithelium : The nuclei are lost in epithelium
 II)Non – keratinized epithelium
➔Nonkeratinized epithelial cells in the superfacial layers do not have
keratin filaments in the cytoplasm
➔ The surface cells also have nuclei
➔ This epithelium is associated with lining of the oral cavity
Difference Between Keratinized & Non-keratinized Epithelium
Keratinized ●Non-keratinized
●Layers – basal,spinosum,granular, ●Layers-basal, intermediate,
cornified layer. surface layer.
●Produce a cornified surface layer. ●Do not produce a cornified
surface layer.
●Prickly appearance . ●Intercellular spaces not
obvious-no prickly appearance
●No nuclei- orthokeratinised ●Stratum superficiale contains
Pyknotic nuclei- parakeratinised nucleated cells
●Filaggrin present. ●Lack filaggrin,butcontain
involucrin.

B)Lamina Propria
Connective tissue of variable thickness that supports the epithelium
called as lamina propria
➔ Two layers-
1)Papillary–between epithelial ridges
2)Reticular
➔ Interlocking arrangement- increases the area of contact – to
facilitates exchange of material between blood vessels & epithelium
➔Ground substance
1)Glycoprotein
2)Proteoglycans
➔ Cells -
1)Fibroblasts
2)Mast cells
3)Macrophages
4)Collagen fibers – type I & type III
5)Elastic fibers
➔ Blood vessles
➔ Nerves
 B)Submucosa
Consists of connective tissue of varying thickness & density
➔ Attaches the mucous membrane to the underlying structures
➔ Contains-
• Salivary glands
• Blood vessels
• Lymph vessels
• Nerves
• Adipose tissue

Subdivisions Of Oral Mucosa

●Keratinized area ● Nonkeratinized area
I.Masticatory mucosa I.Lining mucosa
II.Vermilion border of lip ● Specialized mucosa
I.Masticatory mucosa
1.Hard palate 2.Gingiva
● Immovable, tightly fixed to the periosteum

1.Hard palate
Zones -
i. Gingival region –adjacent to the teeth
ii.Palatine raphe–extending from the
incisive papilla posteriorly
iii.Anterolateral area – fatty zone
between the raphe & gingiva
iv.Posterolateral area – glandular zone

2.Gingiva
Extends from the dentogingival junction to the alveolar mucosa
➔ May be keratinized or non keratinized but most often is
parakeratinized
➔ The gingiva is limited on the buccal surface by mucogingival
junction which separates it from alveolar mucosa

Parts of gingiva–
1)Marginal gingiva-
➔The free gingival is the
terminal edge of the gingival
which is usually about 1mm
wide and surrounds the teeth
➔The free gingival forms one
of the walls of the gingival
sulcus and is separated from
the attached gingival by a
groove called free gingival groove.

2) ATTACHED GINGIVA:-
➔It is the continuation of the free
gingival and extends up to the
alveolar mucosa.
➔The attached gingival is
separated
from the alveolar mucosa by a
mucogingival sulcus.
➔The width :- →3.5-4.5 mm in
the
maxillary anterior region
→3.3-3.9mm in the mandibular
anterior region.
→Posteriorly the width of the
attached gingival is less.

3) INTERDENTAL PAPILLA:-
➔ It is the part of gingival that fills
the space between two adjacent
teeth.
➔ It is a shallow V shaped space
surrounding the tooth.
➔ It is bounded on one side by the
tooth and on the other side by
the free gingiva.
➔ From oral or vestibular
aspect,
the surface of the interdental
papilla is triangular.

4) Col -
➔ The depressed part of
interdental papilla is
called COL.
➔ Col is covered by thin
non-keratinized
epithelium.

II.Vermilion ZoneThe trasitional zone

between the skin of the
lip & the mucous
membrane of the lip
➔ The line that separates
the skin from the
vermilion zone is termed
as the vermilion border
➔ Keratinized

Non-kereatinized
Lining mucosa
➔Found on the
1.lip& cheek
2.vestibular fornix & alveolar mucosa
3.Floor of the mouth
4.Inferior surface of the tongue
5.Soft palate
➔ Relatively thick, non-keratinized epithelium & a thin lamina propria

1)Lip & Cheek

➔Non-keratinized satratified squamous epithelium
➔Attached firmly – lip – to orbicularis oris
– cheek – to buccinator
➔Loose connective tissues contains fat & minor mixed
salivary glands
➔Glands ––– lips – situated in submucosa
––– cheek – glands are larger & usually found between the
bundles of buccinator & sometimes on it’s outer surface
2. Vestibular fornix & alveolar mucosa
Non-keratinized
➔ Loosely connected to the underlying
structures
➔ Gingiva and alveolar mucosa are
separated by the mucogingival junction
➔ Minor mixed salivary glands

3. Floor of the mouth➔Non-keratininzed stratified

squamous
epithelium
➔ Loosely attached to the underlying structures
➔ Submucosa contains adipose
tissues
➔ Sublingual glands lie close to the covering
mucosa in the sublingual folds

5. Soft Palate➔Non-keratinized
stratified
squamous epithelium
➔ Highly vascularized &
reddish in colour
➔ Lamina propria shows a
distinct layer of elastic
fibers
➔ Contains an almost
continuous layer of
mucous glands
➔ Also contains taste buds
Specialized Mucosa
Dorsal Lining Mucosa

➔Superior surface of the

tongue is rough & irregular
➔A “V” shaped line divides it
into anterior part or body
(2/3rd) & a posterior part or
base
➔Nerve supply-
➢ Body – lingual branch of
trigeminal nerve
➢ Base –
glassopharyngeal nerve

Papillae of The Tongue

1)Filiform papillae
2)Fungiform papillae
3)Circumvallate
papillae
4)Foliate papillae

1)Filiform papillae
● On the anterior 2/3rd
● Numerous, fine painted,
cone shaped- gives velvet appearance
● Keratinized epithelial prejections don’t contain taste buds

2)Fungiform papillae
● Mushroom shaped, round, reddish
● Scattered between the filiform papillae
● Contain few(1-3) taste buds on their dorsal surface

3)Circumvallate papillae
● Present in front of V-shaped terminal sulcus
● 8-10 in number
●Lateral surface of the epithelium contain numerous taste buds
●The duct of small serous glands called von Ebner’s gland open
through it
4)Foliate papillae
●Present on posterolateral part of the tongue
●May contain taste buds
 Clinical Considerations

Sublingual Rout of Drug Administration

Sublingual administration is where the dosage form is placed under
the tongue
Rapidlyabsorbed by sublingual mucosa

MUCOCELE

Salivary gland lesion

oftraumatic origin that forms
when the main duct of
minor salivary gland is torn
with subsequent
extravasation of mucous
into the fibrous connective
tissue so that a cystlike
cavity is produced.
Most commonly occur on
the lower lip

Fordyce’s granules
Sebaceous glands are
frequently included in the
line of fusion between the
maxillary and mandibular
processes
Are found just beneath the
buccal mucosa along the

line of occlusionUsually occur

bilaterally,
unilaterally or in groups as
small (1-2mm) slightly
elevated colored spots
They produce a yellowish
rough plaque
Fissured Tongue (Scrotal
Tongue)Malformation manifested
clinically by numerous
small furrows or grooves
on the dorsal surface
Often radiating out from
a central groove along
the midline of the tongue
Is usually asymptomatic
Although some patients
may complain of mild
burning soreness.

Geographic tongue(Benign Migratory

Glossitis)It consists usually of multiple
areas
of desquamation of the filiform
papillae of the tongue in an
irregular circinate pattern.
The central portion – sometimes
appears inflamed
The border – may be outlined by a
thin yellowish line or band
The areas of desquamation remain
for a short time on one location
and then heal appears in another
location.
It may persist for weeks or months
and then regress spontaneously,
only to recur at a later date.
Histologic features - The
hyperplastic epithelium
shows focal collection of
neutrophils designated as
Munro’s abscess within
the epithelium.

Lingual thyroid
It is an anomalous condition

in which follicles of
thyroidtissue are found in the
substance of the tongue
possibly
Arising from a thyroid anlage
which failed to migrate to its
position.
Clinically it appears early in
life chiefly during puberty and
adolescence.
It appears as a nodular mass
in or near the base of the
tongue in the general vicinity
of the foramen caecum, most
often at the midline.

Median Rhomboid GlossitisThis

congenital abnormality of
the tongue is due to failure of
the tuberculum impar to retract
before fusion of the lateral
halves of the tongue.
An ovoid or rhomboid- shaped
reddish patch on the dorsal
surface of tongue immediately
anterior to the circumvallate
papillae.
It is a flat or slightly raised area
and has no filiform papillae.
Hairy tongue

It is characterized
byhypertrophy of the filiform
papillae of the tongue with
lack of normal
desquamation and form a
thick matted layer on the
dorsal surface
The color may vary from
yellowish white to brown
or even black depending
upon their staining

Traumatic Ulcers (Decubitus Ulcer)May be due to – biting,

toothbrush trauma, external
irritant
‘Cotton roll injury’ - most
common iatrogenic injury
Most commonly occurs –
lateral border of the tongue,
buccal mucosa

Aphthous UlcerDevelopment of painful,

recurring solitary or
multiple ulcerations
May be due to-
bacterial infection;
immunological
abnormalities; iron, vit.
B12 or folic acid
deficiency, allergy

References

Orban’s Oral Histology & Embryology 2011, 13th Edition, St. Louis: Mosby Elsevier.
McDonald RE, Avery DR, Dean J. Dentistry for the Child and Adolescent 2004, 9th Edition, St. Louis:
Mosby Elsevier.
Pinkham, Casamassimo P, Fields H, McTigue D, Nowak A. Pediatric Dentistry Infancy Through
Adolescence 2005, 4th edition, Philadelphia: London : Elsevier Saunders.
Shafer’s Textbook of Oral Pathology 2012,7th Edition, St. Louis: Mosby Elsevier.