the ppt demonstrate the structure of the oral mucosa and its function expressing the keratinocytes and non keratinocytes and the classification of oral mucosa.

1. Oral Mucosa
DR. Mahitabe Elgamily
Part 1

2. Objectives
1. Definition
2. Functions
3. Histologic structure of mucosa
a-Keratinized epithelium
b-Non keratinized epithelium
c- Non-keratinocytes
d-Lamina propria
e-Submucosa
4-types of the mucosa

3. Externally
with the skin
(at the lips)
Internally
with the moist mucosa of
the pharynx
It shows some of the properties of each
1-Oral mucosa
(definition)Oral mucosa is the moist mucous membrane lining the inside of
the mouth & its connected

4. It resembles the skin in
It is stratified.
Limit the diffusion across it
in both directions
It resembles the
GIT in
Bathed in tissue fluid.
High rate of turn over

5. 1.Protection:
 It acts as a shield protecting underlying
structures from chemical, thermal and
mechanical effects.
 It also acts as biological barrier against bacteria
and their toxins.
2-Oral mucosa
(Functions)

6. 2. Sensory:
 It has several nerve endings that
respond to temp., touch and pain.
 Also it provides taste sensation and
some reflexes as swallowing,
gagging and water satisfaction

7. 3-Secretory:
 Major and minor salivary glands open on the
surface so keeps it always moist and provide
washing effect.

8. 4.Thermal regulation:
 It is mainly obvious in animals through painting
their skin and evaporation of saliva.

9. 5.Permeability &absorption:
 Mucosa of floor of mouth is very thin so it
allows rapid absorption of drugs.
(sublingual nitrates)

10. 3-Histologic structure of oral
mucosa
consists of:
Oral epithelium
Lamina propria
Separated by basement membrane.
Attached directly to underlying structures or
through submucosa

11. Oral mucosa
Epithelium Basement membrane Connective tissue
Keratinized
 Stratum basale
 Stratum spinosum
 Stratum granulosum
 Stratum cornium
Non keratinized
 Stratum basale
 Stratum intermedium
 Stratum superfaciale
Basal lamina
(ultrastructure)
Lamina
lucida
Lamina
densa
Lamina
propria
Sub
mucosa

12. Oral epithelium
• It is formed of Stratified Squamous Epithelium s.sq.e that either may be
Keratinized Non-keratinized

13. Character of keratinocytes
1- present in sheets.
2-stained with H&E.
3-Have tonofilaments.
4- attached by
desmosomes
5-a vascular

14. 1. Keratinized oral epithelium
Formed of 4 layers named according to the morphology or
shape of cells into:
A. Basal.
B. Spinous.
C. Granular.
D. Keratin.

15. A.Oral epithelium (Basal cell layer)
1-Single layer of columnar cells
2-protein synthetizing cell so…
number of organelles.
3- Has tonofilaments
-Formed by free ribosomes
-gathered into bundles to form tonofibrils.
-They are the primary synthetic product of these
cells.

16. 4-least differentiated cells in the oral epithelium.
5-They undergo mitosis, one of the daughter cells
 remains as progenitor (stem) cells.
 The other will differentiate(amplifying).
Basal cell layer

17. N.B
 The basal cells are the progenitor cells of
thin epithelia (floor of the mouth)
 while the thick epithelia (eg cheek and
palate)the progenitor cells are situated in
the lower 2-3 layers (basal and para
basal) and they are called stratum
germanativum.
Basal cell layer

18. Turn over
Time necessary to replace all the cells in the epithelium
OR /Time taken by a cell to divide and pass through the entire
thickness of epithelium
Skin: 52 to 57 days
keratinized epithelium (Gingiva): 41to 57 days
Non keratinized epithelium (Cheek): 25 days
1. Time of the day.
2. Stress.
3. Cytokines.
4. Regional differences (k & non k)
5. Inflammation ( slight infl……..stimulate mitosis)
( severe infl……..reduction in proliferation)
Def
Rate
Factors affecting

20. 2. Spinous (prickle) cell layer (stratum
spinosum)
• Rows of polyhedral cells.
• The spinous cells appears larger than the basal ones.
• the most active protein forming cells: contain RER
mitochondria, golgi, and tonofilaments.
• The stratum basal and first layers of stratum spinosum are
called stratum germinativum as they give rise to new
epithelial cells

21. • Desmosomes bind these cells together.
• So during histologic preparation the cells shrink except at the areas
where they are held together by desmosomes. This gives them the
prickly appearance.

22. • The superficial cells of prickle cell layer
and the lower granular cell layer contain
small rounded bodies called:
Odland's bodies (keratinosome)
• Membrane coated granules
• Have internal lamellate structure.
• Originate from Golgi app OR RER.
• Form on inter cellular agglutinating
material.

23. 3. Granular cell layer (stratum granulosum)
• 2-3 layers of flat cells larger than the spinous cells &
superficial to them.
• Least active in protein synthesis.
• Contain numerous basophilic keratohyaline granules.
• E.M of the granules
small and irregular
formed by ribosomes
associated with tonofillament.
• Function:
Form the matrix in which the filaments of the
keratin layer are embedded.(filagrin)

24. 4. Keratin layer (stratum cornium)
1– It is the final stage of maturation of keratinized epith.
2- Composed of keratinized squamae (about 20) larger
and flatter than the granular cells.
3- All cell organelles have disappeared.
4-The cornfied cells don’t synthesize protein.
5- keratin = compacted tonofillament+ filaggrin
(filament aggregation)

25. 6- the desmosomes are altered to allow for desquamation
(corneodesmosomes)
7- the lost squamae are replaced by cells from the underlying layers.

26. Cellular events during
keratinization1- Disappearance of cellular content.
2- Decrease in cell size so the tonofillament appear tightly packed.
3-Thickening of the cell membrane…. Protein keratolinin.
4-Odland bodies discharge their content into the intercellular space
forming permeability barrier
(limit the passage of substances)
5-Keratohyaline granules… matrix in which the filaments of the
keratin layer are embedded (Filagrin).
6-The desmosomes are altered to allow for desquamation
(corneodesmosomes)

28. Types of Keratinized epithelium
• Parakeratinized 75%
retain pyknotic nuclei &
remenant of organelles
• Orthokeratinized
15%
no nuclear remnant
 This is a normal
appearance in the oral
mucosa but in the skin this
means psoriasis

29. Desmosomes
(macula adherans)• DEF:
localized spot-like structures specialized for cell-to
cell adhesion. they are type of junctional complexes.
• SITE :
Randomly arranged on the lateral sides of plasma membranes.
• FUNCTION:
-Form adhesive bonds
-Gives mechanical strength to tissues
frequently subjected to mechanical forces.
• STRUCTURE:
• Thickening of 2 adjacent cell membranes.
• 2 attachment plaques.
• Tonofilaments.
• Intervening extracellular structure.

32. DESMOSOMES HEMI DESMOSOMES
1- Thickening of 2 cell membranes 1- Thickening of one cell membrane
2- Two attachment plaques 2- One attachment plaques
3- Tone filaments 3- Tone filaments
4- Extra cellular adhering Substance 4- Extra cellular substance
5- Between 2 cells 5- Between cell and basement membrane

33. Desmosomes &
Hemidesmosomes

34. Comparison between
keratinized &
non keratinized epithelium

35. Keratinized Non keratinized 10%
shape& Keratin
production
 Produce cornified layer.
 Epi rete pigs are long& slender.
 Thinner layer than non ker.
 Doesn’t produce cornified layer.
 Epi rete pigs &short and blunt.
 Form thicker layer .
layers  Basal
 Prickle
 Granular
 Cornified
 Basal
 Intermediate
 superficial
Basal  Single layer of columner cells.
 High no of organelles.
 Protein synthesing cell.
 Tono filaments gathered (tonofibrils)
 Least differentiated cell.
 Tono filaments don’t gather …remain dispersed.
Prickle  Rows of polyheadral cells.
 Most active in protein synthesis.
 Smaller cells than non k epi.
 Large intercellular space.
 High prickly appearance.
 Larger cells than the k epi.
 Small intercellular spaces.
 Less prickly appearance.

36. keratinized Non keratinized
Odland bodies :
- have lamellate structure
- discharge a barrier at the junction of the
granular and cornified layer .
Odland bodies:
-circular, amorphous core,
-discharge the content in the intercellular space, the discharge
have different composition and don’t form an effective barrier
as the keratinized epithelium.
 Keratohyaline granules:
- appear in the surface of this layer but
- more regular and spherical,
- not associated with tonofillament,
- contribute to thickening of the cell membrane.
Produce loricrin not filagrin
Granular
layer
 Least active
 Keratohyaline granules:
- small & irregular
-associated by tono filaments
- form matrix in which the filaments are
embedded( filaggrin)
 Absent
Cornified
layer
 Present (about20 layers)
 Don’t synthesize protein
 Dense Filament + filaggrin
 Absent

37. keratinized Non keratinized
Cornified
layer
 Present (about20 layers)
 Don’t synthesize protein
 Dense Filament + filaggrin
 No organelles, dehydrated, flat
 Absent
Superficial
cell layer.
 absent  Cells slightly more flattened than the preceding layers.
 Retain their nuclei.
 Dispersed tonofilament.
 Decreased number of cell organelles.
 Surface layer don’t dehydrate.
 Thickened cell membrane but not like the keratinized one.
 Form stretchy surface that can tolerate compression.

38. N.B : all cells of both keratinized or non-
keratinized epithelium are called keratinocytes.
As these cells can form keratin at any time.
Example :
 the cheek mucosa is non-keratinized, but at the
line of meeting of occlusal surfaces of teeth,
there is a keratinized area called Linea alba.
 This keratinization occurs due to continuous
irritation of this area evoking cells to produce
keratin

39. Smoking may also lead to excessive keratinization of the hard palate and
inflammation of minor salivary glands(stomatitis nicotina)
the cause of nicotine stomatitis is thought to be chemical or thermally
induced keratosis

41. Non-Keratinocytes
1- Don’t turn into keratinocytes or share in keratin formation
2- Amount to about 10% of the cell population in epithelium.
3- Not arranged in rows or sheets, but found scattered in mucosa
4- Lack desmosomes( except Merkel cells) so lack tonofillament
5- Have a clear halo around the nucleus, and so known, clear cells.
6- Not stained with routine H&E stain
General characteristics:

43. Types
1- Melanocytes.
2- Langerhans cells.
3-Merckls cells.
4-Inflammatory cells.

44. Melanocytes Langerhans Merckle Defensive
Site  Basal layer of oral
epithelium.
 Supra basal layers (higher
level cells).
 basal cell layer  various epithelial levels
in clinically normal
mucosa.
 They are immigrants,
found among the
epithelial cells and then
infiltrate through
epithelium to reach the
surface.
Function  Melanin producing
cells.
 Elaborate melanin in
the form of small
granules called
melanosomes.
 If injected in epi cell
Called…melanophore.
 If engulfed by C.T
macrophage….melanop
hage
 Immunologic function
recognize the antigenic
material and present it to
the T helper lymphocyte
 Able to activate the T
lymphocytes
 Neural cells
specialized for
responding to
touch or pressure
stimuli.
 There is synapse
like junction
between it and the
nerves
 They are involved in
inflammatory response.
 Associated with
Langerhans cells.
 They are transient

45. Melanocytes Langerhans Merckle Defensive
origin  From neural crest cells and migrate to
epith
 Bone marrow  May be from division
of keratinocytes
shape  Lack desmosomes and tonofilaments.
 Dendritic (long) pass through several
layers.
 E.M…
 the cells have rod or
flask shape granules
(Berbeck granules
 Convoluted nucleus.
 No tonofilament
 Has tonofilaments
and desmosomes
 Nucleus is deeply
invaginated.
 Has small granules
contain neuro
transmitters
N.B  The number of melanocytes per unit
area in the oral mucosa or skin is
constant in white or dark race
 The color difference is related to the
activity of the melanocytes in
melanin production and
 rate of breakdown.
 Capable of limited
division
 Can move on and out
the epi.
 Can pass
through the
epithelium to
the surface.

46. Melanocyte Langerhans Merckle Defensive
stain  silver impregnation
technique or DOPA
reaction
 gold chloride or CD1a
surface antigen
 PAS +ve  CD3 for T-lymphocytes
 CD20 for B-lymphocytes.

47. Pigmentation of the oral mucosa
External Internal
Amalgum tatoo
Melanin
hemoglobin

48. Basement membrane
Def :
It is the junction between the epithelium and the C.T
Function :
1. Diffusion barrier (control exchange of molecule).
2. Filtration barrier (kidney)
3. Orient location and movement of epith cells.
4. Elastic support for epith cells.
Shape :
It may be irregular with long slender retepigs or short blunt
processes

49.  They are the downward projections of epithelium in the underlying
CT . These ridges interdigitate with upward projecting connective
tissue papillae.
 In masticatory mucosa: has greatest NO. of the epithelial ridges per
unit area (long- slender)
(adaptation to function and applied force)
 In lining mucosa: they are less numerous, broader and shorter.
Epithelial retepigs:
Function of epith rete pigs:
1. Increase surface area
2. Provide better attachement.
3. Better distribution of force
4. Large interface for metabolic exchange (no
B.V in epi)

50. By L.M:
 1-4 m, appears as undulating line as a result of
epithelial rete pegs interdegitate with C.T papilla
 The main components of basal lamina are type
IV collagen, the glycoproteins laminin, and
proteoglycans.
 Stained with: PAS (proteoglycans)
bright structure less
Basement membrane under the microscope:

51. By E/M:
lamina lucida (clear zone):
 Electron lucent (very little staining in the EM) 20-40
nm.
 Collagen XVII+ Integrin +Laminin332
 Contain bullos pemphigoid antigen)
lamina densa (dark zone):
 Electron dense 50 nm.
CollagenIV+ heparin sulfate+ laminin.
lamina fibro reticularis :
 Small loops of finally banded fibrils (anchoring
fibrils collagen VII) below the lamina densa and
inserted into it
 Collagen fibers run through the loops.
 Originates from fibroblasts of the C.T
Epithelial origin
Epithelial origin

52.  Antibodies against the basal lamina can cause blistering diseases (separation of
epi from the CT)
Ex: bullous pemphegoid which occur at the level of the lamina lucida
 Also mutation in laminin332 gene or integrin also cause blistering

53. Loss of cohesion between the keratinocytes due to
loss of desmosomes
pemphigus vulgaris.
thickening of the epithelium resulting
Epithelial disorders
Acanthosis Acantholysis

54. atrophy
hyperplasia
hyperkeratosis
ulceration

56. Lamina propria
• It is composed of dense connective tissue of
variable thickness which plays a role in
supporting and securing the nutritional and
metabolic exchange into the epithelium.
• It may attach the periosteum or overlay the
submucosa.
 Morphologically, the lamina propria may be
divided into two areas
1- papillary layer
2- reticular layer.

57. The papillary layer:
• has predominantly loose
network of collagen fibers,
associated with reticular fibers
(argirophilic ).
• Subjacent to the basement
membrane the fine collagen
fibers become concentrated
with reticulin fibers.
 This layer may be absent
(if rete pigs are absent or too
short).
 The reticular layer:
• closely packed thick collagen
fibers.
• They are arranged horizontally in
the direction of minimum
extensibility to prevent mucosal
deformation.
• Few elastic fibers are found to
restore deformed collagen.
• Always present

59. Lamina propria is formed of:
• Cells
• Blood vessels
• Lymphatic drainage
• Nerve supply
• Fibers
• All these components are embedded in amorphous
gel-like ground substance formed of glycoproteins
and proteoglycans.

60. SiteFunctionFeaturesCell
Throughout Lamina
propria
Fibers and G.S formationStellate or elongated with
abundant RER
Fibroblast
Throughout L.P.Precursors of
macrophage
Spindle or stellate shape, dark
stained nucleus contains many
lysosomal vesicles
Histocyte
Areas of chronic
inflammation
PhagocytosisRounded with pale staining nucleus
contains lysosome and phagocytes
vesicles
Macrophages
Areas of inflammationPhagocytic, blood, bone
precursor of macrophage
Rounded with dark staining kidney
shape Nucleus moderate amount
of cytoplasm
Monocytes

61. SiteFunctionFeaturesCells
Sub epithelialSecrete inflammatory
mediator
as histamine heparin,
serotonin (allergic
reactions)
Rounded or oval with
basophilic granules
Mast cell
Acute inflammationPhagocytosis and cell
killing
Rounded with lobed
nucleus contains
lysosomes and granules
Polymorph nuclear cells
(PMNL)
Acute and chronic
inflammation
Humeral and cell
mediated immunity
Rounded with dark
stained nucleus and
scurry cytoplasm with
some mitochondria
Lymphocyte
Chronic inflammationSynthesis of antibodiesCart wheel nucleus,
eccentric with abundant
RGR in cytoplasm
Plasma cell
Lining vascular charnelsLining blood and
lymphatic channel
Associated with basal
lamina, contain numerous
vesicles
Endothelial cell

62. Blood supply:
Branches of the external carotid artery:
• Superior labial of facial arteries & infraorbital
arteries: Supply blood to the upper lip
• Inferior branches of the facial & mental
arteries: Supply the lower lip
• Greater and lesser palatine arteries: Supply the
palate
• Sublingual artery: Supplies the sublingual gland
and the floor of the oral cavity
Veins
Veins of the oral cavity generally
follow the arteries and have the
same names.
• The veins of the palate drain into
the pterygoid venous plexus.
• The lingual veins of the tongue
drain into the internal jugular
vein.

63. The lymphatic drainage of the oral
cavity
• Lymph from the upper lip, teeth, lateral parts of the anterior part of the tongue,
and gingiva drains into the submandibular lymph nodes.
• Lymph from the lower lip and apex of the tongue drains into the submental
lymph nodes.
• Lymph from the medial anterior portion of the tongue drains into the inferior
deep cervical lymph nodes, and the posterior portion of the tongue drains into
the superior deep cervical lymph nodes.

64. The nerves of the oral cavity
• Greater and lesser palatine nerves and
nasopalatine nerves (CN V2):
Supply the roof and palate
• Lingual nerve (CN V3):
Serves the floor of the mouth
• Buccal nerve (CN V3):
sensory innervation to the skin and mucosa of
the cheek
• Lingual, palatine, nasopalatine, and superior
alveolar nerves:
Supply the gingiva

65. Nerve supply to the tongue:
• Lingual nerve : touch and temperature (general
sensation) for the anterior two-thirds of the tongue
• Chorda tympani nerve (CN VII): Part of the facial
nerve; contains taste fibers from the anterior two-
thirds of the tongue.
• Hypoglossal nerve (CN XII): Innervates the muscles
of the tongue (except for the palatoglossus)
• Glossopharyngeal nerve (CN IX): Supplies general
and taste for the posterior one-third of the tongue
• Internal laryngeal nerve (CN X): Branches supply
general sensation to a small part of the posterior
part of the tongue

66. Submucos
a• The lamina propria may be or
• It is present in most regions of the oral cavity.
• the mucosa may be firmly or loosely attached to the
underlying structures according to the degree of density
of the submucosa.
directly attached to the
underlying periostium
or bone
separated from it by sub
mucosal layer.

67. Content :
 adipose tissue.
 salivary glands.
 large blood vessels.
 large nerves.
 The medium sized arteries branch in
the submucosa and their branches
enter the lamina propria to form
subepithelial capillary plexus.

68. • Sensory nerve fibers in the submucosa are myelinated,
Loose the myelin sheath
Terminate in the lamina
propria
as sensory nerve ending
Enter between the epithelial cells
As free nerve ending
• Unmyelinated visceral nerve fibers supply the smooth
muscles of the blood vessels and glands.

69. Oral mucosa
Masticatory
mucosa
(keratinized)
Lining mucosa
Non (keratinized)
Specialized
mucosa
Classification
Gingiva Hard palate Firmly
attached
Loosely attached
Soft palate – lips- cheek- inferior
surface of the tongue
Alveolar mucosa- vestibular fornix-
floor of the mouth

70. Masticatory
mucosa

71. Gingiva
Covers the teeth neck and part of the
alveolar bone.
Pale pink in color.
Pigmented in colored races.
Separated from the alveolar mucosa
by a scalloped line called
mucogingival junction (healthy line)
The mucogingival junction not
present on the palatal aspect of the
upper jaw.

72. Gingiva
Free gingiva Attached gingiva
Interdental
gingiva
 Keratinized except sulcus & col
 No sub mucosa
 directly attached to cervical cementum or
periostium of bone

73. 1-Free gingiva
 It extends along the cervical level of the tooth at the labial,
buccal and lingual surface.
 It is freely movable and extends to the bottom of the gingival
sulcus or slightly below.
 It is taper to knife edge (gingival margin)
 free gingival groove:
 Separates the free gingiva from attached gingiva.
 appears as shallow V shaped notch corresponding to heavy
epithelial rete pegs found between free and attached gingiva.
(1-1.5 mm)
 Formed due to functional impact on free gingiva

75. Gingival sulcus
 Def:
It is the space between the gingiva and the tooth
surface
 Histology :
• lined by non-keratinized epithelium
• Lack epi rete pigs in normal conditions.
• Lymphocytes and plasma cells commonly seen in the CT for defense
dto constant presence of bacteria so act as a barrier to prevent bact
penetration or its toxins
 Depth:
• varies from 0 to 6 mm with average 1.8 mm.
• The more shallow the sulcus the more favorable the condition of
the gingival margin.