This document provides an overview of oral histology. It discusses the structure and functions of oral mucosa, including the epithelium, basement membrane, lamina propria, and submucosa. It describes keratinized and non-keratinized oral mucosa, as well as the different types of oral mucosa based on function. The roles of non-keratinocytes like melanocytes, Langerhans cells, and Merkel cells are outlined. Details are given on the histology of gingiva, including the clinical appearance and characteristics of free gingiva, attached gingiva, and interdental papillae.

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1ST
Edition
New Insight Into
Oral Histology
MO'men Gamal AboDa

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Oral Mucosa
The oral cavity is unique in structure as
1. Contains the teeth & taste buds
2. The salivary glands discharge their secretion into it
Thus it serves a variety of functions (such as perceive & sense)
Functions
Protection
(The major function)
The role of (Lining & Masticatory M.)
Protects oral deeper tissues, organs & soft tissues from
1. Oral Cavity Environment which normally contains microorganism
(that cause infection if they gained access to the tissues)
2. Normal Activities (Biting & Chewing food)
Protects oral Soft tissues from
1. Surfaces abrasion
Sensation
(provides considerable information about oral cavity events)
The role of (Specialized M.)
Oral Mucosa contains
a. Receptors that respond to temperature, touch & pain
b. Taste Buds, which are responsible for taste sensation (Not found anywhere else in the body)
Secretion
The role of (Salivary Glands)
Oral Mucosa contains
a. Major salivary glands are situated far from the mucosa & release their secretions via long ducts passing
through the O.M
b. Minor salivary glands are associated with the oral mucosa
NB: Saliva: the major secretion contributes to the maintenance of the surfaces moisture

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General Histology of the tissue (from outside inward)
I-Epithelium (of the stratified squamous variety)
a. Keratinized epithelium (4 cell layers named from their
morphologic appearance)
Basal Layer Spinous (Prickle) Layer Granular Layer Cornified Layer
Stratum Basal Stratum Spinosum Stratum Granulosum Stratum Corneam
Site
Resting on the Basement
Membrane
Resting on the Basal Layer Resting on the Spinous
Layer
On the Top of the
surface
N. Single cell layer 4-8 cell layer 2-3 cell layer 2-4 cell layer
Shape
Cuboidal cells
(high cuboid)
Irregularly Polyhedral
cells
(larger than the basal cells)
Flat cells
with regular & close to
each other surfaces
(larger & wider than the
spinous cells)
Flat (squamea) Cells
(larger & flatter than
the granular cells)
Function
1-Mitotic Function
(DNA Synthesis providing
new cells)
1-Mitotic Function
2-Protein Synthesis
(most active)
NB: the proteins differ
from those made in the
basal cells
1-Mitotic Function
2-Protein Synthesis
(at lower rate)
Protection
Characteristics
Contain
*Desmosomes:
Proto-plasmic junctions
connect the cells to each
other
*Hemidesmosomes:
Proto-plasmic junctions
connect the layer to the
C.T
(abut on the basal
lamina)
Contain
*Intercellular Spaces;
contain
Glyco-protein
Glycos-amino-glycans
Fibro-nectin
*Intercellular
bridges: bridges connect
the cell to each other
across which the
tonofibrils pass from cell to
cell (by L.M)
NB: By E.M,
-the intercellular bridges
are desmosomes
-the tonofibrils are bundles
of tonofilaments
So, it consists of
Desmosomes &
Tonofilaments
Contain
*Nuclei: show signs of
Degeneration &
Pyknosis
*Kerato-hyalin granules:
Basophilic (Blue staining
with H&E)
So, this layer is named
granular
-Fewer in
Para-Keratinized epith.
-More in
Ortho-keratinized epith
*Tonofilaments: are
denser in quantity & seen
associated with
Keratohyalin granules
*Odland body: Lamellar
granule forms in the upper
spinous & granular cell
layers
Contain
*All Cells: are
acidophilic (red staining
with H&E)
*Pyknotic
Nucleus; it’s termed
as
Para-Keratinized
epith.
*NO Nucleus;
it’s termed as
Ortho-keratinized
epith.

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NB: -Epith. may be Para-keratinized, Ortho-keratinized or non-keratinized depending on their location
-All epithelial cells contain keratin intermediate filaments (common feature)
-Reti Pegs: epithelial ridges protrude toward the lamina propria (So make epith. & C.T Interdigitation)
Mucous Membrane: Surface line body cavities which communicate with the external (e.g. Oral cavity)
-The O.M structure is composed of two layers, epith. & C.T
- The O.M structure varies in different oral cavity regions (Due to function adaptation)
*Odland Body
Site: *Upper Spinous & Granular layers of Keratinized S.S epith
*Upper Intermediate layer of None-keratinized S.S epith
Shape: Ovoid shape, membrane bound granules
Lamellar in Keratinized S.S epith & Granular in None-keratinized S.S epith
Containing: Lipids & Cholesterols
Function: Acts as a Barrier against 1. Water loss 2. Microorganisms’ invasion & disuamation
Epith. Para-keratinized Ortho-keratinized
Cornified
cells
Pyknotic Nucleus & other organelles (partially
lysed) until they desquamate
No Nucleus
Granular
cell
Fewer Kerato-hyaline granules More Kerato-hyaline granules

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b. Non-keratinized epithelium (Only 3 cell layers)
NB: it differs primarily from keratinized (Because they do not produce a Cornified surface layer)
Basal Layer Intermedium layer Superficial Layer
Stratum Basal Stratum Intermedium Stratum Superficial
Sit
e
Resting on the Basement Membrane Resting on the Basal Layer On the Top of the surface
N. Single cell layer cell layer cell layer
Shape
Cuboidal cells
(Similar to keratinized type)
Large Ovoid
No prickly appearance
(larger than the cells of the Stratum
Spinosum)
Slightly Flat Cells
Fu
n.
1-Mitotic Function
(DNA Synthesis providing new cells)
1-Mitotic Function
2-Protein synthesis
Characteristics
Contain;
*Desmosomes: connect the cell
to each other
*Hemidesmosomes:
connect the layer to the C.T
Contain;
*No Intercellular Spaces; as the
cells do not have a prickly appearance
*No Intercellular bridges:
But attached by desmosomes & other
junctions
*Odland body is present
-Serves a similar function BUT
-Have granular rather than lamellar
contents
Contain;
*Nuclei
*Few organelles
*Dispersed filaments
Keratinized Non-keratinized
Region Masticatory Mucosa Lining Mucosa
Layers Number 4 layers
Basal - Spinous - Granular - Keratinized
3 layers
Basal - Intermedium - Superficial
Reti Pegs Tall & Narrow Short & Wide
Basal Similar to each other
Spinous
VS
Intermedi
um
Sh. Prickle cells -smaller No prickle appearance - larger
Ch. Contain;
*Intercellular Spaces
Contain;
*No Intercellular Spaces
Odland Body Lamellar Contents Granular Contents
Granular Present Absent
Keratinized Present Absent

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II-Basement Membrane (Basal Lamina by E.M)
Definition: the junction (distinction) between
the epith. & C.T
Origin: epithelium in origin
Shape: made up of
*Lamina Lucida: Clear zone just below the
epith.
*Lamina Densa: Dark zone just above the C.T
III-lamina propria
Definition: C.T of variable thickness
Function: Supports the epithelium mechanically (elastic) & Nutritionally
It’s divided into two parts (for descriptive reasons)
Papillary Portion Reticular Portion
Site
Part of the Lamina propria which is enclosed within
the epithelial Reti Pegs
Part of the Lamina propria which is attached to the
underlying tissue “either Alveolar Bone Or
Submucosa”
Structure
Rich in Papillae so it’s named P.P
This papillae
-Have interlocking arrangement with the epithelial
ridges
-Have variation in length & width in the different
areas
So, this portion is of a variable depth
-In some areas, are either very short or lacking
So, this portion is absent in those areas
(Such as: the alveolar mucosa)
-Contain Sensory nerves ending of various types
Rich in Reticulin Fibers so it’s named R.P
NB The Contact (surface) area between the lamina
propria & epithelium is increased by
1. The interlocking arrangement of the Papillary
portion with the epithelial ridges “Reti Pegs”
2. Undulating course they have
3. Projections found at the base of each epithelial cell
This additional area: Facilitates exchange of materials
between the epith. & the C.T Blood vessels
By the R.P, the lamina propria may
-attach to the periosteum of the alveolar bone,
which is in “Gingiva” OR
-Overlay the Submucosa, which is in different regions
such as “Soft palate & Mouth Floor”

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IV-Submucosa
Definition: C.T of varying thickness & density
Function: It attaches the mucous membrane to the underlying structures
Direction: arrange perpendicular to the underlying bone surface
NB: The attachment may be loose or firm depends on the Submucosa character
Components:
1-B.Vs;
-Larger arteries divided into smaller branches which enter the lamina propria where they divided again to form
a Subepithelial Capillary Network in the papillae
-The veins originating from the capillary network course
back along the path taken by the arteries
2-Nerves; Myelinated nerve fibers “as they traverse the
Submucosa”
But lose their myelin sheath “before splitting into their
end”
3-Lamphatic Vessels; accompany B.Vs
4-Glands 5-Adipose tissue

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Non-Keratinocyte
Defi: Cells that reside & perpetuate themselves in (the oral epithelial & epidermal
territories)
Differ from the epithelial cells in; 1. Unable to form keratin
2. Lack desmosomal attachment to surrounding cells….So, they shrink (Except:
Merckel Cells)
3. Having a Clear Halo around the nucleus (by L.M)….So, they are called “Clear Cells”
Melanocytes Langerhans cells Merkel cells Inflammatory cells
Site
Basal region
(may be found in the C.T)
(most conspicuous)
Superficial layers of
epithelium
Basal region In case of inflammation,
they migrate into oral
epith.
Shape
Dendritic Cells with
-long extensions between the surrounding epithelial cells
Branched Cells with
-Desmosomal
connections with
their neighbors
-Sparse
tonofilaments
Different Types include
-lymphocytes
-monocytes
-neutrophils
-granulocytes
-mast cells (occasionally)
Origin
Neural Crest Bone Marrow Neural Crest
Division of
epithelial cells from
“keratinocytes”
Bone Marrow
Function
Melanin Production & Storage
NB:
*Melanin is stored in specific granules
which
-appear as intercellular brown dots (by
L.M)
-are transferred from the
melanocytes to the basal epithelial
cells
-are broken down by lysosomal action
in the superficial epithelial layers
*Difference in color of skin in different
racial groups is due to
1. Differences in melanin synthesis rate
2. Melanin granules size
3. Slow breakdown of adjacent
keratinocytes
i.e. in dark races ,there is
-increased melanocytes activity, but
their number not differ
Act as Antigen-
presenting cells
Because they have
specific immune
receptors on their
cell membranes
Acts as Sensory
cells that respond
to touch because
they are associated
with nerve
terminals inside
the epithelium
Defensive Cells
NB: they do not
commonly live &
perpetuate themselves
resident cells

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Types of Oral Mucosa (according to the Keratinization)
a. Keratinized (Para & Ortho) include: 1-Masticatory Mucosa
2-Vermilion border of the lips
3-Papillae of tongue
b. Non-Keratinized include: 1-Lining Mucosa
Types of Oral Mucosa (according to the function)
Masticatory Lining (reflecting) Specialized (sensory)
Parts of oral mucosa sharing in
mastication
Parts of oral mucosa lining deep tissues
& organs
Tongue Dorsum which
responsible for taste sensation
Madeupof
Hard palate & Gingiva
Except: -Gingival Cole
-Sulcular epith.
All the oral surfaces except for
masticatory mucosa & Tongue dorsum
Firmly Loosely
lip & cheek Mouth floor
Soft palate Vestibular fornix
Tongue ventral S Alveolar mucosa
Include: -Gingival Cole -Sulcular epith.
Tongue Doral surface
Characteristics
•Pink in color
•To withstand masticatory forces
It’s
-Keratinized
-Firmly attached to bone
-Not stretchable
-Immovable
-largely resistant to compression
*Similarities:
-Epithelium: thickness &
keratinization
-Lamina propria: thickness,
density & firmness
*Differences: their Submucosa
(as the gingiva has no
Submucosa)
•Not equally exposed to such forces &
adapting itself to
-Contraction & Relaxation of cheeks, lips
& tongue
-Mandible movements produced by
mastication muscles
So it’s
-Non-Keratinized stratified squamous
-Firmly or Loosely attached to bone
-Distensible
NB: •It covers the musculature
•Interface between epithelium & C.T is
gently undulated
•Lamina Propria: few, short & wide
papillae
•Generally compressible & moveable,
relative to the underlying tissue (Due to
the presence of a Submucosa between
lamina propria & underlying tissue
“usually muscle tissue”
To perform its sensory function
It
•is Non-keratinized
•Contains the taste buds
NB: These are 2 areas with a slightly different structure;
1-Dentogingival junction 2-Vermilion border of the lips (red zone)

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Gingiva
•Macroanatomy (CLINICAL APPEARANCE)
Free gingiva Attached gingiva Interdental papilla
Site Part of gingiva at the gingival
margin of each tooth
Part of gingiva covers the alveolar
process of the dental arch
Part of gingiva fills the spaces
between the teeth
Clinicalappearance
Color Pink (similar to attached
gingiva)
Opaque pink
Shape *NO Stippling appearance
(NOT similar to attached
gingiva)
*Stippled Surface (with small
pinpoint depressions) give the
surface an orange-peel
appearance
Cause: the heavy Reti Pegs,
histologically
Importance: functional
adaptation to mechanical impact
*NO Stippling appearance
*Has pyramidal (triangular)
shape between anterior teeth
& Tent shape between
posteriors
*Surfaces:
-Cole: non-keratinized portion
of the interdental papillae
adjacent to the tooth surface
-Facial surface: keratinized as
the rest of the gingiva
Other NB: -it’s tissue is mobile or
free from the underlying
tooth surface (NOT similar)
NB:
-Stippling Degree differs in
different areas of gingiva & with
different individuals
-Stippling disappears in some PD
diseases as Edema of
inflammations
Function: Prevent food from
impaction or lodging during
mastication
Surfaces:
NB: *Free gingival groove
Shape: •Anatomically: Dividing line between free & attached gingiva
•Histologically: V shaped notch of heavy epithelial ridge
Direction: runs parallel to the margin of the gingiva
Normal Distance: 0.5 to 1.5 mm (increase in some PD diseases as Pockets)
*Mucogingival junction: Scalloped junction between the pink attached gingiva & the red alveolar mucosa
Clinical importance: Measuring the width of attached gingiva by demarcating its apical border
(This determines the support level that the tooth has by the PDL & alveolar process)
*Interdental groove: The gingiva appears slightly depressed between adjacent teeth
Due to depression of the alveolar process between eminences of socket

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Hard Palate
•Macroanatomy (CLINICAL APPEARANCE)
•Microanatomy Gingiva Hard palate
Epithelium
Thickness Thick Thick
Keratinization Stratified squamous Keratinized
Except: Gingival Cole & Sulcular epithelium
which covered by Non-keratinized
Stratified squamous Keratinized
Reti Pegs Numerous, Tall & Narrow
(So, they help to make the epith. very
adherent & relatively immovable)
Tall & Wide
(So, they help to make the epith. very adherent
& relatively immovable)
Lamina Propria Papillary & Reticular parts Papillary & Reticular parts
Submucosa Absent Irregularly dense fibrous tissue
Divided into;
••Anterior part: filled with adipose tissue (Fatty
Zone)
••Posterior part: with palatine salivary glands
(Granular Zone) So, it acts as a cushion
Attachment
Type Firmly Firmly
To Connect Lamina propria directly to the
underlying bone
Connect Submucosa to the underlying bone
Regions Site Clinical
Appearance
Gingival
region
adjacent to the teeth smooth
Palatine
raphe
(median
region)
-from the incisive papilla, anteriorly
-to the beginning of the soft
palate, posteriorly
a firmer feeling
Antero-lateral
region
(Rugae)
Fatty region between the median
raphe & gingival region, anteriorly
whiter pink tissue
that is immobile &
firm
Postero-
lateral region
Glandular region between the
median raphe & gingival region,
posteriorly
a cushioned feeling

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Lip Histology consists of 3 zones: Outer labial skin - Transitional Zone - Labial Mucosa
•Microanatomy Vermillion border Skin Labial Mucosa
Epithelium
Thickness Thin Thick Thick
Keratiniza
tion
Stratified squamous
Para-keratinized
Stratified squamous
Keratinized
Stratified squamous
Non-Keratinized
Reti Pegs Numerous, densely arranged,
Tall & Narrow
Tall & Narrow Short & Wide
Lamina
Propria
Definition C.T support epithelium Mechanically & Nutritionally
Contains Papillary & Reticular parts
Submucosa
Definition
Contains *Only occasional sebaceous
glands
(So, it is subject to drying &
therefore requires moistening
by the tongue)
*Few & short papillae
*Many sebaceous glands,
sweat glands & hair
follicles
*Minor Salivary glands
(Labial Salivary Glands)
Attach
ment
Type Firmly Firmly Firmly
To Connect Submucosa to the underlying muscle
NB: •Boundary between red zone & Labial mucosa occurs where keratinization of the transitional zones ends
Vermilion border of the lip (only in humans)
•Transitional Zone between the skin & the mucous membrane of the lip
Color: Red Zone Due to
1. With Thin Translucent Keratin layer
2. Papillae reach deep into the epithelium
3. Papillae carry large capillary loops close to the surface
So, blood is visible giving the red color to the lips

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Lining Mucosa
Buccal
Mucosa
Labial
Mucosa
Mouth Floor Tongue
Ventral
Soft Palate Gingival Cole
& Sulcus
Epith. Stratified Squamous Non-keratinized
Reti Pegs Short & Wide
Lamina P.
Papillae
Dense C.T with & Short papillae
irregular numerous few
Submucosa Dense collagen fibers strands
with loose C.T (fat & small
mixed glands) between
them
Contains
Adipose tissue
Cannot be
identified as a
separate layer
Relatively loose
Contains
Mucous glands
& taste buds
Absent
Buccal glands
are in
Submucosa
Labial glands
are larger &
between
buccinators
muscle
bundles
(sometimes
on its outer
surface)
Sublingual
glands lie in the
sublingual fold
close to
covering
mucosa
NB: distinct layer
of elastic fibers
separating it from
Submucosa
NB Connects lamina propria to
the thin fascia of the muscles
Mucous M. on is
thin & loosely
attached to
underlying
structures (to
allow free
mobility of the
tongue)
Mucous M. is
smooth &
relatively thin
Mucous M. is
highly
vascularized &
reddish in color,
noticeably
differing from the
pale color of the
hard palate

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Specialized Mucosa (Dorsum of the tongue)
Macroanatomy
*Sulcus terminals: V shaped line divided the dorsal surfaces of the
tongue into anterior & posterior parts
*Anterior 2/3 part “Papillary”: Contain all types of lingual papillae
*Posterior 1/3 part “Lymphatic”: Contain lymphatic tissues (Lingual
Tonsils)
Microanatomy
Papillae Filiform Fungiform Circum-vallate Foliate
Number Most abundant Lesser than Filiform 8 to 12 4 to 11
Site Over the entire surface of the tongue In the V shaped groove Near tongue base
on either side
Shape Thick Conical hairs Mushrooms
On top of the surface
(Show as reddish dots)
Mushrooms
Sunk below the surface
-are surrounded by a circular
groove of oral mucosa
NB: The deepest part of the
grooves contain the opening
of Von Ebner Salivary G ducts
Mushrooms
On top of the
surface
parallel with each
other
NB: may not easily
be visible clinically
Epith. Thick keratinized Thin keratinized
NB: The thinness of the
epithelium allows the red
of the blood vessels to
show through
This is responsible for the
red color of these papillae
Thin keratinized Thin keratinized
Taste
Buds
Without Variable number on its
superior surface
Numerous on the vertical
(Surface) side, facing the
groove
Numerous on each
side
Function Purely
mechanical
function
Taste Sensation 1. Taste Sensation
2. Main source of salivary
lipase
3. Their serous saliva serve to
wash out the soluble
elements of food
Taste
Sensation
NB: -All lingual papillae covered with Ortho-keratinized or Para-keratinized

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Taste Buds
Shape: Barrel-shaped
Origin: epithelial organs of special sense
Site: Lingual Papillae (except: Filiform), Soft Palate & Pharynx Walls
Histology: runs from B.M to the top surface of the epith. & contact
with saliva by taste pore
“Taste pore: Superficial opening in surface epithelial provide direct connection between taste bud & oral cavity”
Types of
cells
I-Taste cells II-Supporting cells
Shape Tall & Spindle shaped cells with a single cellular
extension (which protrude into the taste pore)
Spindle shaped cells
Function 1. Specialized epithelial cells for taste sensation 1. Support the actual taste cells
2. Production of the taste pore substance (which is
responsible for Digestion of the tasted food)
Types of taste sensation of the tongue:
Site
Bitter Posterior part
Salt lateral sides,
anteriorly
Sweet Anterior part, near tip
Sour lateral sides,
posteriorly