classification and features of oral mucosa.

1. ORAL MUCOUS
MEMBRANE
By
Dr.Surrendra Reddy

2. CONTENTS
 Introduction
 Classification
 Functions of oral mucosa
 Junction of epithelium & lamina propria
 Lamina propria
 Submucosa
 Basic components of connective tissue
- Cells
- Fibres
 Ground substance
 Blood supply
 Nerve supply
 Structural variations
 Development and age changes

3. INTRODUCTION
 Term mucous membrane is used to describe the
moist lining of the gastro intestinal tract, nasal
passages and other body cavities that
communicate with exterior
 In the oral cavity- ‘oral mucous membrane or oral
mucosa’

4.  Oral mucosa consists of epithelium and connective
tissue termed lamina propria
 Oral epithelium- stratified squamous type & arranged in
a number of distinct layers or strata
 It is attached by the submucosa to the underlying
structures which maybe bone or muscle

5. CLASSIFICATION
Based upon primary function served
1. Masticatory Mucosa (25%)
2. Lining Mucosa (Covers 60% of total area)
3. Specialised Mucosa (15%)
Based upon keratinisation
1. Keratinised
 Orthokeratinized
 Parakeratinized
2. Non-keratinised.

6. Based upon Location
1. Buccal Mucosa.
2. Lingual Mucosa.
3. Palatal Mucosa.
4. Labial Mucosa.
5. Alveolar Mucosa.

7. Masticatory mucosa:
 bound to bone
 does not stretch
 bears the forces generated when food is chewed

8. Lining mucosa:
 Covers the musculature and is distensible
 Adapts itself to contraction & relaxation of the lips,
tongue & to movements of mandible

9. Specialized mucosa:
 Bears taste buds which have a sensory function

10. FUNCTIONS OF ORAL MUCOSA
 Defense
 Lubrication
 Sensory function
 Protection

11. DEFENCE:
 The integrity of the oral epithelium is an effective
barrier to the entry of micro organisms
 Impermeable to bacterial toxins
 Secretes antibodies
 Efficient humoral and cell mediated immunity

12. LUBRICATION:
 Secretion of salivary glands keeps the oral cavity
moist
 Prevents mucosa from drying and cracking
 A moist oral cavity helps in speech, mastication,
swallowing & in perception of taste

13. SENSORY:
 Oral mucosa is sensitive to touch, pressure, pain &
temperature
 Touch sensation in the soft palate results in gag
reflux

14. PROTECTION:
 Protects deeper tissues from mechanical forces
resulting from mastication and abrasive nature of
food stuffs

17. ORAL EPITHELIUM
 the oral epithelium
constitutes the primary
barrier between the oral
environment and deeper
tissues.
 It is a stratified squamous
epithelium consisting of
cells tightly attached to
each other and arranged
in a number of distinct
layers or strata.

18.  The epithelial surface of the masticatory mucosa is
inflexible, tough, resistant to abrasion, and tightly
bound to the lamina propria.
 It results from the formation of a surface layer of
keratin, and the process of differentiation that
produces it is called keratinization or cornification .

19. EPITHELIAL PROLIFERATION
AND TURNOVER
 The oral epithelium, like other covering and lining epithelia,
 maintains its structural integrity by a process of continuous
 cell renewal in which cells produced by mitotic divisions in
 the deepest layers migrate to the surface to replace those that
 are shed (Nakamura et al., 2007 ). The cells of the epithelium
 can thus be considered to consist of two functional
populations:
 a progenitor population (whose function is to divide and
 provide new cells) and a maturing population (whose cells are
continually undergoing a process of differentiation or
maturation
 to form a protective surface layer).

20. Amplifying Cells
Stem cells
PROGENITOR
CELLS
• Slow dividing
• Maintain basal cell layer
• Rapidly dividing
• Form other cell layers.

21. TURN OVER TIME
The time taken for a proginetor cell to pass through
the entire epithelial thickness and reach the surface
Skin : 52 – 75 days
Gut : 4 – 14 days
Gingiva : 41 – 57 days
Cheek : 25 days
Junctional Epithelium : 5 - 6 days

22. BASAL LAYER
 The basal layer (sometimes called stratum basale)
is a layer of cuboidal or columnar cells adjacent to
the basement membrane.
 Occasionally, the term proliferative or germinative
layer (stratum germinativum) is used to describe
the cells in the basal region that are capable of
division

23. JUNCTION OF EPITHELIUM & LAMINA PROPRIA
 Undulating interface b/w oral
epithelium & lamina propria
 Epithelium forms ridges protruding
towards lamina propria- ‘EPITHELIAL
RIDGES’
 These ridges interdigitate with the
connective tissue papillae- surface
area+ Forces are distributed over a
larger area+ Major interface for
metabolic exchange
 Masticatory mucosa has longer &
more no. of papillae; whereas lining
mucosa has shorter & lesser no.

24.  Junction there are 2 different structures with similar
names:-
 Basement membrane – LM level
 Basal lamina- EM level

25. BASEMENT MEMBRANE
 The interface between
connective tissue and epithelium
 Includes reticular fibres
 1-4 µm wide
 Relatively cell free
 Stains positively with
PAS method- bright,
structureless band
 Contains neutral
mucopolysacharides

27. Lamina lucida:
 Clear zone
 40 nm wide glycoprotein layer
 Contains proteins responsible for attaching cell to
basal lamina- interacting portions of
hemidesmosome associaed membrane proteins
(collagen XVII & integrins)
 Also contains type 4 collagen and an antigen bound
by the antibody KF1
 ALSO contains laminin 5and bullous pemphigoid
antigen
 Laminin and type 4 collagen promotes epithelial cell
growth

28. Lamina densa:
 50 nm
 Homogenous fibrillar collection of ECM molecules;
Type 4 collagen coated with heparan sulphate in
chicken wire configuration & laminin
 Anchoring fibrils which contain type 7 collagen
forms loops and are inserted into the lamina densa
 Type 1 and type 2 collagen fibres run through these
loops
 Other proteins contained- heparan sulfate
proteoglycan (perlecan); Nidogen & Fibulin

29.  Except Sublamina densa, all layers are synthesized
by Epithelium
 Clinical significance-
- LM- lamina lucida & densa is thicker than in EM
probably because, stains also react part with
subepithelial connective tissue
- Pemphigoid, mucosa blisters- antibodies attack
specific components of basal lamina i.e bullous
pemphigoid antigen, collagen XVII of basal lamina
- Mutation in laminin 5 or integrin gene- causes
blistering- causes seperation of epithelium from
connective tissue at the level of lamina lucida

32. Functions of basement membrane:
 Promotes differentiation
 Promotes peripheral nerve regeneration and growth
 They tend to prevent metastases

33. LAMINA PROPRIA
 Connective tissue of variable thickness that
supports the epithelium
 Theoretically, 2 layers:-
 Papillary- associated with the epithelial ridges
 Reticular- b/w papillary layer & the underlyng
structures. Net like fibre arrangement
 Basic difference-
 Papillary- collagen fibres are thin & loosely
arranged; many capillary loops are present
 Reticular- collagen is arranged in thicker bundles.
Lie parallel to the surface plane

36. SUBMUCOSA
 Consists of connective
tissue of varying thickness
and density
 Attaches mucous
membrane to underlying
structures
 Glands, blood vessels,
nerves & adipose tissue are
present in this layer

37. BASIC COMPONENTS
 Cells + extracellular matrix
protein fibres + ground substance
collagen OR elastic- most resistant
part of stroma
Cells
cells that belong to the immune
system- e.g.macrophages & mast
cells; plasma cells; white blood
cells.
Cells that are intrinsic components
of connective tissue.
E.g. fibroblasts, undifferentiated
mesenchymal cells, pigment cells,
fat cells

40. FIBROBLAST
 Most common cell of connective
tissue.
Functions-
 - Synthesize-
 - collagen & elastin
 - glycosaminoglycans
 - proteoglycans
 - glycoproteins
 - growth factors
2 types based on the activity-
 fibroblast-active cell
 fibrocyte- quiescent cell

41. FIBROBLAST FIBROCYTE
1. cell- larger in
size
Smaller in size.
Elongated, spindle
shaped
2. cytoplasm-
abundant,
irregularly
branched
Thin, fewer
cytoplasmic
extensions
3. Nucleus- large,
ovoid, pale staining
Fine chromatin
Prominent
nucleolus
Smaller, darker
elongated nucleus
Condensed
chromatin
4. Organelles-
RER & golgi
complex abundant
& well developed
Less amount of
RER & golgi
apparatus

42.  Present in close relation to
collagen fibres.
 Fixed cells- not mobile
 Fibroblasts- fibroblasts; not
other types of cells
 Myofibroblasts- morphology:
fibroblast
- Behavior like smooth
muscle
- cell- actin+ myosin–
wound
- contraction

44. CLINICAL SIGNIFICANCE
 Regenerative capacity- very high
 Main cell- FIBROBLAST
 Inflammation, trauma, surgical incision- connective
tissue is formed- SCAR

45. UNDIFFERENTIATED MESENCHYMAL CELLS
 Small cells
 oval nucleus
 prominent nucleoli
 fine chromatin
 thin cytoplasmic processes
 Function- gives rise to other
types of cells (totipotent in
nature)

46. PIGMENT CELLS
 Brown pigment in cytoplasm- MELANIN
 Most abundant- skin, iris & choroid of
eyeball
 Cells that synthesize melanin-
melanocytes (neural crest origin)
 Melanophores/chromatophores- modified
fibroblasts. Cells that do not produce but
engulf in melanin released by other cells-
stellate shape
 Function- prevent light from reaching
other cells

47. FAT CELLS/ADIPOCYTES
 Cells that store fat in large amounts
 Aggregations- adipose tissue

48. On the basis of number of fat
globules classified as-
Monolocular adipocytes/
White fat tissue-cell
 In these cells single large
and central fat globule is
present.
 Cytoplasm is peripheral &
less.
 Due to compression of fat
globule, nucleus is flattened
in shape & peripheral

49. Multilocular adipocytes/
Brown fat tissue cell
 2-3 fat globules seen in the
cytoplasm around nucleus
 Cytoplasm is more in
quantity.
 Nucleus is rounded & found
in the centre
 These adipocytes form
Brown Fat.

50. LEUKOCYTES/WBC
 6000-10000/µl- normal
range in blood
 According to the type of
granules in their
cytoplasm and the shape
of their nuclei, divided into
two groups:
 Granulocytes- neutrophil,
eosinophil & basophil
 Agranulocytes- monocyte,
lymphocyte

51. Granulocytes- terminal non-
dividing cells
 2 types of granules:
 Specific granules- bind
neutral, basic, or acidic
components of the dye
mixture and have specific
functions.
 Azurophilic granules- Stain
purple and are lysosomes.
 Golgi complex, RER &
mitochondria- poorly
developed.

52. Agranulocytes-
 Do not have specific granules
 But contain azurophilic
granules (lysosomes).
 Nucleus is round or indented.
 Includes lymphocytes &
monocytes

53.  Function- Cellular and humoral
defence.
 DIAPEDESIS- the process in which
WBC’s leave the venules & capillaries
by passing between endothelial cells
and penetrating the connective tissue.
(Gr. dia, through; pedesis, to leap)
 Diapedesis is increased in infection &
inflammation
 CHEMOTAXIS- The attraction of
specific cells by chemical mediators.
Significant event in inflammation
through which leukocytes rapidly
concentrate in places where their
defensive properties are needed

54. NEUTROPHILS
 60% to 65% leukocytes; actively motile
 5000/µl of blood
 12-15µm in diameter
 Consists of a characteristic dense nucleus
 2-5 lobes
 Pale cytoplasm
 Contains numerous fine violet – pink granules

55. Granules are of two types:
Primary or
azurophilic
granules
Secondary
specific
granules
Smaller
More numerous
Contain :
1. lysozyme, type4
collagenase, lactoferrin
2. Alkaline phosphatese
3. Plasminogen activator
4. Leucocyte adhesion
molecules
Larger, coarser
Contain-
1.
myeloperoxidase
2. hydrolases-
lysozymes,
elastase,
proteinase

56.  Life span- 4-8 hours in blood and 4-5 days in tissue
 Functions of neutrophils :
 Chemotaxis
 Phagocytosis
 Killing of microorganism- oxygen dependent &
independent pathways

57. EOSINOPHILS
 2-3% of WBCs
 12-15 µm in diameter
 150/µl of blood
 Usually 2 nuclear lobes
 Cytoplasm- coarse, deep red
staining granules
 Granules- contain basic proteins,
cell adhesion molecules and
cytokines
 Life span- 4-8 hours in blood and
4-5 days in tissue

58. Functions :
 Mild phagocytosis
 Produces major basic protein –
kill larvae of parasite- protection
against parasitic infection
 Secretes aryl sulphate B which
inactivates slow reacting
substances released from the
mast cells – prevents anaphylaxis
 Secretes enzyme histaminase –
destroys local hormone histamine
– anti allergic response

59. BASOPHILS
 0.5-1%
 30 cells/µl
 Coarse intensely basophilic granules
 Granules contain- Heparin, histamine & 5-HT
 In tissues- mast cells
 Life span- 4-8 hours in blood and 4-5 days in tissue

60. MAST CELLS
 Also called mastocytes or
histaminocytes
 Round/oval shape
 10-13µm in dia
 Small, spherical centrally
located nucleus

61. • Cytoplasm- basophilic secretory
granules (0.3-2µm in diameter)
• Granules- metachromatic
• METACHROMASIA- property of certain
molecules to change the color of some
basic dyes
• Granules contain- heparin
- histamine
- neutral proteases
- eosinophil chemotactic
factor of anaphylaxis
• Release- leukotrienes
- slow reacting substance of
anaphylaxis
• PARACRINE SECRETION

62. 2 populations
Connective tissue mast cell Mucosal mast cell
- Skin & peritoneal cavity - intestinal mucosa &
lungs
- Larger in size - smaller
- Contain heparin - chondroitin sulfate
 Surface- IgE receptors
 Function- storage of chemical mediators of the
inflammatory response

63.  Some of the stains used for mast cells-
 PAS
 Toludine blue
 Azure A
 Thionin
 Alcian blue
 Aldehyde fuchsin
 Chlorocacetate esterase

64. CLINICAL SIGNIFICANCE
 Release of chemical mediators stored in mast cells-
IMMEDIATE HYPERSENSIVITY. E.g anaphylactic
shock

65. MACROPHAGES & MONONUCLEAR
PHAGOCYTE SYSTEM
 Described as fixed if they
are attached to fibers
 10-30µm in size
 Oval/kidney shaped
nucleus- eccentrically
located
 EM: irregular surface with
pleats, protrusions &
indentations.
 Well developed golgi
complex, RER, lysosomes

66.  Monocytes & macrophages- same
cells in different stages of
maturation
Function-
- phagocytosis
- production of cytokines,
chemotactic factors- CELL
MEDIATED RESISTANCE
- antigen processing & presentation
- removal of damaged extracellular
components during physiological
involution process

67. monocytes
macrophage
s
Protein synthesis- RER, golgi complex
Cell size
Lysosomes
Microtubules, microfilaments

68. Skin- LANGERHAN
CELLS
CNS- MICROGLIAL
CELLS
Liver- KUPPFER
CELLS
Bone-
OSTEOCLASTS
Different organs different names

69. CLINICAL SIGNIFICANCE
 Macrophages epitheloid cells ( cell size &
form clusters)
 Macrophages- fuse together- multinuclear giant cells

70. MONOCYTES
 Comprise 2-8 % of the blood
leukocytes
 No.- 350 cells/µl of blood
 12-20µm in dia
 Agranulocytes

71.  Nucleus ranges from being a deeply indented ovoid
shaped or roughly kidney shaped
 Fine reticulated chromatin network
 Cytoplasm- stains a pale grayish blue color
 Fine pinkish purple azurophilic granules can sometimes
be seen in the cytoplasm

72. Functions:
 Serve as immediate precursors
for macrophages
 Phagocytosis
 Antigen presenting cells
 As mediator of inflammation
they are involved in the release
of prostaglandins

73. PLASMA CELLS
 B-Cells- on stimulation-
plasma cells
 Produce antibodies
 Usually seen in areas of
chronic inflammation; often
perivascularly

74.  Large ovoid cells
 Cytoplasm is basophilic- RER
 Eccentrically placed spherical nucleus
 Coarse, compact heterochromatin (numerals of a clock)
alternating with light areas- Clock face appearance or cart
wheel appearance

75.  Life span- short- 10-20
days
 Mature plasma cells
contain Russell bodies

76. LYMPHOCYTES
 Non-granular leukocytes
 20% to 30% of the blood
leukocytes
 2000-4000/µl
 Large aggregations-
lymphoid tissues
 Small lymphocytes- 9-12µm
in dia.
 Large lymphocytes- 12-
16µm in dia
 Small>large

77.  Spherical cells
 large round/indented nuclei
 only a thin rim of basophilic cytoplasm
 Life span- Few days or even years

78.  Functionally of 3 types-
 B lymphocytes- mature in bone marrow itself- HUMORAL
IMMUNITY
 T lymphocytes- mature in thymus- CELL MEDIATED
IMMUNITY
 - CD4+- Helper T-Cells
 - CD8+- Cytotoxic T-Cells
 NK cells- morphologically similar to lymphocytes but
functionally different- INNATE IMMUNITY
 Attacks virus-infected cells and cancer cells without
previous stimulation

79. PERICYTES
 Pale staining connective
tissue cells
 Long slender cytoplasmic
processes
 Lie immediately external to
the endothelium of blood
capillaries and small
venules.
 Called pericytes because of
their perivascular position
 Role in connective tissue
repair- neovascularisation
(formation of new blood
vessels): give rise to smooth
muscle cells OR fibroblasts

80. ENDOTHELIAL CELL
 Normally associated with a basal lamina
 Lines vascular channels throughout the lamina
propria
 Contains numerous pinocytic vesicles

81.  Functions :
 Mild phagocytosis
 Produce major basic protein – kill larvae of
parasite- protection against parasitic infection
 Secretes aryl sulphate B which inactivates slow
reacting substances released from the mast cells –
prevents anaphylaxis
 Secretes enzyme histaminase – destroys local
hormone histamine – anti allergic response

82. FIBRES OF CONNECTIVE TISSUE
Collagen fibres-
Most abundant protein in human body
30% of dry weight
Thin, elongated structure
20-90nm in dia
EM- characteristic transverse striations at 64
nm periodicity)
Staining charateristics-
 gross- white
 H&E- light pink
 Van gieson- pink
 masson’s trichome- blue
 Ag impregnation- brown

83.  Physical properties-
 Resist tensile forces
 Polarized light- split into 2
beams & refracted in
different directions-
BIREFRINGENCE
 Weak acid or alkali- swells &
softens
 Strong acids- destroyed

84.  Collagen in the lamina propria is primarily type 1
and type 3
 Type 4 and type7 occur as part of basal lamina
 Type 5 maybe present in inflamed tissue

85. SYNTHESIS OF COLLAGEN
 By fibroblasts, chondroblasts, osteoblasts, odontoblasts
 Principal amino acids making up collagen-
- GLYCINE (33.5%)
- PROLINE (12%)
- HYDROXYPROLINE (10%)
- HYDROXYLYSINE
 Tropocollagen collagen
 Tropocollagen- length: 280nm
- width: 1.5nm
 3 subunit polypeptide chains- triple helix
polymerises

87.  Type I, II, III- tropocollagen
microfibrils (3.5nm in dia)
fibrils (20-200nm in dia)
fibres (1-12µm in dia)
Hydrogen bonds+
hydrophobic
interactions
Cross-links- lysyl
oxidase

88. RETICULAR FIBRES
 Type of collagen- type III; loosely packed
 Thin- 0.5-2µm in diameter
 PAS +ve- high sugar content
 High affinity for Ag salts- ARGYROPHILLIC

89. Type I Type III
Coarser Finer
Evenly thickened Uneven in thickness
Forms bundles
No branching seen
Form a network (reticulum)
Branching & anastamosis
No bundles
Can be stained with H&E Not visible in H&E
Ag impregnation- black
Less hexoses-1% More carbohydrates-6-12%
Difference between type I & type III collagen

91. ELASTIC FIBRES
 Single, no bundles
 Branch & anastomose
 Thinner than collagen- 0.1-
0.2µm
 3 types of fibres-
- OXYTALAN
- ELAUNIN
- ELASTIC
 Development is in 3
successive stages.

92. OXYTALAN
Oxys- thin greek
Dermis & basal lamina
Not elastic
No elastin protein
Resistant to pulling forces
Bundle- 10nm microfibrils
Glycoproteins- fibromodulin I, II & fibrillin
ELAUNIN
Irregular deposition of elastin between
oxytalan fibres
Around sweat glands, dermis
ELASTIC FIBRES
Elastin deposits in centre of fibre bundles
surrounded by a thin sheath of microfibrils
Stretch easily in response to tension

93.  Present in most regions of oral mucosa
 More abundant in lining mucosa

94. PHYSICAL PROPERTIES
 Stretchable
 Refractile- shining lines in
unstained preparations
 Stretched fibres- birefringence
 Fenestrated membranes- non-
fibrillar form- wall of some
blood vessels

95. CHEMICAL NATURE
 Protein- elastin (proelastin- fibroblasts
& smooth muscle cells)
 Valine+alanine+desmosine+isodesmosi
ne
 Weak acids, alkali, boiling- no effect
 Elastase- digest
 EM- central amorphous core
 Outer layer of fibrils- fibrillin
 Staining characteristics-
 Orcein
 Aldehyde fuschin
 Verheoff’s method

96. GROUND SUBSTANCE
 Colorless, highly hydrated & transparent
 Viscous- barrier to penetration by invaders
 Fills the spaces between cells & fibres
 Lubricant
 3 classes- glycosaminoglycans
- proteoglycans
- multiadhesive glycoproteins

97. GLYCOSAMINOGLYCANS
 GAG’s OR acid mucopolysaccharides- linear
polysaccaharides formed by repeating disaccharide
units- uronic acid (glucuronic acid or iduronic acid)
& hexosamine (glucosamine or galactosamine)
 Polysaccaharide chains+protein core-
PROTEOGLYCAN
except HYALURONIC ACID
 Intensely hydrophilic- OHˉ, COOHˉ, SO³⁻4

98. PROTEOGLYCANS
 Test tube brush- central core- protein & side
bristles- carbohydrates
 Proteoglycan- 80-90% carbohydrate
 Core- protein; GAGs- dermatan sulfate,
chondroitin sulfate, keratan sulfate &
heparan sulfate.
 Acidic groups+basic groups of collagen

99.  Proteoglycans-
 Extracellular matrix-
AGGRECAN- dominant
proteoglycan in cartilage
 Cell surface proteoglycans-
mainly epithelial cells-
SYNDECAN,
FIBROGLYCAN
Functions-
 Anchors cell to the matrix
 Bind with growth factors

100. BLOOD SUPPLY
 More rich & profuse arrangement than that of skin
 Blood flow greater than that of skin at normal temp;
maximum in gingiva
 Heals more rapidly than skin- no arteriovenous
shunts but has rich anastomoses of arterioles &
capillaries
 Blood supply is derived from arteries that run
parallel to the surface in the submucosa

101.  When the submucosa is absent, in the deep part of
the reticular layer
 These vessels give off progressively smaller
branches that anastamose with adjacent vessels in
reticular layer before forming an extensive capillary
network in the papillary layer just subjacent to basal
epithelial cells

102.  Regional variations-
 E.g. cheek- 1 papilla- 1 capillary loop. Arterioles
more branching & tortuous path
- tongue filiform papillae- variable no. of capillaries
- fungiform & circumvallate papillae- arterioles

103. ARTERIAL BLOOD SUPPLY TO ORAL MUCOSA
Oral region Sub terminal branches
Upper lip Superior labial artery
Upper Gingiva
anterior Anterior superior alveolar artery
lingual Major palatine artery
buccal Buccal artery
posterior Posterior superior alveolar artery
Hard palate Major palatine artery
Nasopalatine artery
Sphenopalatine artery
Soft palate Minor palatine artery
cheek Buccal artery
Terminal branches of facial artery
Posterior alveolar artery
Infraorbital artery

104. Oral region Sub terminal branches
Lower lip Inferior labial artery
Mental artery
Branch of inferior alveolar artery
Lower Gingiva
anterior buccal Mental artery
anterior lingual Incisive and sublingual artery
posterior lingual Inferior alveolar and sublingual
artery
posterior buccal Inferior alveolar and buccal artery
Floor of mouth Sublingual artery
Branch of lingual artery
tongue
anterior 2/3rds Deep lingual artery
Posterior third Dorsal lingual artery

105. Micrographs showing the relationship between capillaries in lamina propria and
overlying epithelium

106. NERVE SUPPLY
 Rich sensory nerve supply
 Primary sensations perceived in the oral cavity –
warmth, cold, touch, pain & taste
 Density of sensory receptors – more in anterior regions
than posterior part of the mouth
 Greatest density- connective tissue papillae are most
prominent
 Touch sensation- most acute in ant.part of tongue &
hard palate
 Touch receptors in soft palate & oropharynx- swallowing,
gagging & retching
 Temp sensation- more acute in vermillion border of lip,
tongue tip & ant.hard palate
 Sensory nerves terminate in free and organised nerve
endings

107.  Within the lamina propria organized nerve endings
are found in papillary region
 They consist of groups of coiled fibers surrounded
by a connective tissue capsule
 They include - meissners corpuscles
- ruffinis corpuscles
- krause bulbs
- mucocutaneous end organs

108. Nerve bundle Intraepithelial
nerves Electron micrograph of free
nerve ending

109. PRINCIPLE SENSORY NERVE FIBERS SUPPLYING
ORAL MUCOSA
Oral region innervation
Upper lip and vestibule Twigs from intra orbital branch of
maxillary nerve
Upper gingivae Anterior , posterior, middle superior
alveolar branches of maxillary nerve
Hard palate Greater, lesser and sphenopalatine
branches of maxillary nerve
Soft palate Lesser palatine branch of maxillary
nerve, tonsillar branch of
Glossopharyngeal nerve, nerve of
pterygoid canal
cheek Twigs from infra orbital branch of
maxillary nerve, superior alveolar
branch of maxillary nerve, buccal
branch of mandibular nerve, some
terminal branches of facial nerve

110. Oral region innervation
Lower lip and vestibule Mental branch of inferior alveolar
nerve, buccal branch of mandibular
nerve
Lower gingivae buccal and lingual Inferior alveolar branch of
mandibular nerve, buccal branch of
mandibular nerve, sublingual branch
of lingual nerve
Anterior 2/3rds of tongue Lingual branch of mandibular nerve
provide fibers carried in lingual
nerve but originating in facial nerve
and passing by way of chorda
tympani to lingual nerve
Posterior third of tongue Glossopharyngeal nerve

111. KERATINIZED ORAL MUCOUS MEMBRANE

112. KERATINISED EPITHELIUM
(ELECTRON MICROSCOPY)

113.  Epidermal/epithelial cells
that secrete keratin
 Shows intermediate filament
protein
 Undergoes: cell division,
maturation and finally
desquamate.
 Increase in volume: from
basal tosuperficial.
 Function : The primary
function of keratinocytes is
the formation of a barrier
against environmental
damage such as pathogens
bacteria fungi viruses heat
UV radiation and waterloss
KERATINOCYTES

114.  Features unique to epithelial cells
1. Presence of keratin tonofilaments as component of
cytoskeleton
2. Intercellular attachment in the form of Desmosomes

115. • Single layer of cuboidal or columnar cells that
rest on basement membrane
• Basal and parabasal cells synthesize DNA & undergo
mitosis. So these cell layers are also called as
Proliferative or Germinative layer.
• Basal cells have basophilic cytoplasm and centrally
placed nucleus, which is hyperchromatic and relatively
large.
• Nucleus is arranged perpendicular to basement
membrane
STRATUM BASALE

116. • Nucleus occupies 1/3rd of cells with evenly distributed
chromatin and 2-3 nucleoli
• Basal cells show ribosomes, mitochondria, golgi
complex, elements of rough endoplasmic reticulum
and few lysosomes indicative of protein synthesizing
activity.
•

117. i) Serrated- heavily packed with tonofilaments
which are adaptations for attachment.
ii) Non-serrated – stem cells – slowly dividing
cells which serve to protect genetic information of
the tissue and provide cells for maturing
compartment

118. Basal cells are attached to basal lamina by
hemidesmosomes.
Epithelial cell-cell contact is made through
desmosomes - macula adherens. These are
anchored intracellularly by tonofibrils.

119. STRATUM SPINOSUM OR PRICKLE CELL
LAYER:
• Seen above basal layer and composed of
several rows of large irregular polyhedral cells
• Show first sign of maturation.
• The intercellular spaces of the prickle layer are
large and distended, with more prominent
desmosomes

120. • cells are large and have centrally placed round or ovoid
nucleus.
• N/C ratio is 1:6
• Cytoplasm is rich in organelles for protein synthesis
• protein synthesized are Fibrillar proteins k/as
cytokeratin
• The concentration of tonofilaments increases and gets
arranged to form bundles.

121.  Cells attached by desmosomes ( number and width is
more)
• This layer is also c/as Prickle cell layer because in
histological sections, cells have a spiny or prickly
appearance.
• Odland bodies are present in upper part of this layer

122. STRATUM GRANULOSUM
Flatter & wider & nuclei show signs of degeneration &
pyknosis.
Nucleus is flattened with long axis parallel to the outer
surface of epithelium.

123. Active in protein synthesis.
Involucrin - soluble precursor protein of the
cornified envelope appears first in the spinosum.
Protein synthesis rate progressively gets
diminished as cell approaches stratum corneum.


124. KERATOHYALINE GRANULES :
 The cytoplasm of cells is filled with basophilic granules
 Size 0.1-1.5 microns
 Size and number increases as the cell moves through
the granular layer
 Angular or irregular and associated with ribosomes
 Contain sulphur rich proteins fillagrin and loricrin which
provide an embedding matrix for the tonofilaments

125. KERATINOSOME OR ODLAND BODIES OR MEMBRANE CONTAINING GRANULES
OR CYTOPLASMIC LAMELLATED BODIES
Modified lysosomes
0.25µm in length.
Rich in phospholipids.
Structure - layers of parallel lamellae consisting of
alternate electron lucent and dense bonds, probably
originating from golgi apparatus.
Lamellar granules discharge their contents -
permeability barrier.

126. STRATUM CORNEUM
Other name is cornified layer and horny layer.
Made up of keratinised squamae, which are larger &
flatter than the granular cells.
Nuclei & other organelles disappear.
The cells are densely packed with filaments

127. Cell surfaces in this layer are more regular &
more closely adapted to adjacent cell surfaces.
The filaggrin a non fibrous inter-filamentous
matrix protien helps in this close adaptation.

128. TYPES OF KERATINIZED EPITHELIUM
Parakeratinized Epithelium :The superficial cells
are dead but retain the pyknotic nucleus
Orthokeratinized Epithelium : The nuclei are lost
in epithelium

130. NONKERATINIZED EPITHELIUM
They do not producea
cornified surface layer.
The cells in nonkeratinizing
epithelium are called as basal,
intermediate, and superficial
layer. ( stratum basale ,
stratum intermediate,
stratum superficiale.)
The cells of stratum
intermedium are largerthan
cells of larger than cells of
stratum spinosum.
There is no stratum
granulosum / nor thereis
stratumcorneum.

131. NON-KERATINOCYTES IN ORAL EPITHELIUM
Constitute about 10% of epithelial cell population. Three major cells which are
all clear cells with a halo around their nuclei.
1. Langerhans cells: found on stratum spinosum (suprabasal) and function in
antigen trapping and processing. Dendritic cells. No desmosomes or
tonofilaments.
2. Merkel cell: Located in basal cell layer (mostly in gingiva). Function as
touch
receptors. Nondendritic. Sparse desmosomes and tonofilaments.
3. Melanocytes: Found in basal cells. Melanin-producing cells (mostly in
gingiva).
Dendritic. Presence of melanin granules (melanosome).
4. Lymphocytes and leukocytes: Inflammatory cells that are not clear cells.
Associated with inflammatory response in oral mucosa

132. Melanocytes are melanin-
producing cells located in the
bottom layer (the stratum
basale).
embryological neural crestand
migrate intoepithelium
establishes contactthrough
dendritic processes
appearclear in H and E stains,
hence called as clear cells or
dendriticcells.
Function: Melanin production
MELANOCYTES

133. Langerhans cells are dendriticcells
(antigen-presenting immune cells)
o
fthe skin and mucosa, and
contain large granules called
Birbeck granules.
 Hematopoietic inorigin.
 Free of melanin, do notgive
dopa reaction.
 presents antigen to Tcells.
Function:
Contact hypersensitivity
Anti tumour immunity
Graft rejection
LANGERHANS CELLS

134.  Merkel cells are found inthe
stratum basale.
 Specialized neural pressure-
sensitive receptorcell.
 Commonly seen in masticatory
mucosa.
 Non dendritic
 Migrate from the neuralcrest.
MERKEL CELL

136. DIFFERENCE
Keratinized
Layers - basal, spinosum,
granular, cornified layer.
Produce a cornified
surface layer.
Prickly appearance.
Nonkeratinized
Layers-basal,intermediate,
surface layer.
Do not produce a cornified
surface layer.
Intercellular spaces not
obvious-no prickly
appearance.

137. No nuclei-orthokeratinised
Pyknotic nuclei-
parakeratinised
Filaggrin present.
Numerous
tonofilaments,keratohyaline
granules present.
Lack filaggrin,but contain
involucrin.
Less developed and
dispersed tonofilments,lack
keratohyaline granules.
STRATUM SUPERFICIALE
CONTAINS NUCLEATED
CELLS

143. KERATINIZED AREAS

144. MASTICATORY MUCOSA
• The epith. is moderately thick and may be
orthokeratinized or parakeratinized .
• B.M. is convoluted (numerous elongated papillae).
• The lamina propria is thick
• It covers immobile structures (e.g. palate and alveolar
process).
• Bound firmly to the periosteum

145. GINGIVA
 Surrounds the neck of the teeth and extends to the alveolar
mucosa.
 It is made up of st. squ. epith. which may be orthokeratinized (15%)
, nonkeratinized (10%) , or parakeratinized (75%).
 The gingiva is limited on the outer surface by the mucogingival
junction which separates it from the alveolar mucosa.
 On the inner surface of the lower jaw a line of demarcation is found
between the gingiva and the mucosa on the floor of the mouth
 On the palate the distinction between the gingiva and the peripheral
palatal mucosa is not so sharp.

147. Mucogengival junction
(keratinized gingiva – right ; nonkeratinized mucosa – left(

148. 1. The gingiva is divided into:
2. The free gingiva.
3. The attached gingiva.
4. The interdental papilla.
 Marginal gingiva (free gingiva)
 Unattached portion of gingiva that
surrounds the teeth in a collar like
fashion.
 Follows a scalloped line on the
facial and lingual surfaces of the
teeth.

149.  Attached gingiva: the firm, resilient immobile portion of
the gingiva which is tightly bound to the alveolar bone
 Extends from free gingival groove to mucogingival
junction
 Width is about 4-6mm. (maxilla 3.5-4.5mm, mandible
3.3-3.9mm)
 Surface has orange peel appearance created by
elevation and depressions (stippling)

150.  Free gingival groove: between the free gingiva
and the attached gingival (0.5 – 1.5 mm at or apical
to the botton of the nonkeratinized gingival sulcus)
 The gingival surface appears stippled (due to epith.
ridges and numerous collagen bundles attaching
the tissue to periosteum)
 The gingiva appears depressed between adjacent
teeth (between the eminence of the socket) and
form slight vertical folds called interdental
grooves

151. Interdental
papilla
Free gingival
groove
Interdental folds
in interdental groove
Mucogingival
junction
Alveolar
mucosa
Free gingiva
Attached
gingiva
(stippled)
Gingival
margin

152. Gingival margin
Free gingiva
sulcus
gingiva
Gingival stippling
Free
gingival
groove
attached
Dentin
Space of
enamel
Sulcular epithelium
Junctional epithelium
cementum
dentino
gingival
fibers
GINGIVA – Micro-Anatomy Gingival

153. THE INTERDENTAL PAPILLA
Part of gingiva that fills the space
between two adjacent teeth
Triangular when viewed from the
vestibular aspect.
In a 3 dimensional view, it is pyramidal between the
ant. teeth and tent shaped between post. teeth.
The central part is concave (below the contact eara) and
is called the gingival col which is covered by thin
nonkeratinized epith.
Col is more vulnerable to periodontal disease

154. THE INTERDENTAL PAPILLA
Part of gingiva that fills the space
between two adjacent teeth
Triangular when viewed from the
vestibular aspect.
In a 3 dimensional view, it is pyramidal between
the ant. teeth and tent shaped between post.
teeth.
The central part is concave (below the contact
area) and is called the GINGIVAL COL which is
covered by thin nonkeratinized epith.
Col is more vulnerable to periodontal disease

155. GINGIVA – MACRO-ANATOMY
Free gingiva
Free
gingival
groove
attached
gingiva
pale
pink
Gingival
stippling
”col region “

156. INTERDENTAL PAPILLA AND GINGIVAL COL
Gingival col( non-
(keratenized
Contact point
Col

157. HISTOLOGY
 Epithelium: gingiva composed of stratified squamous
epithelium.
 It is parakeratinized in 75%, orthokeratinized in 15% and
nonkeratinized in 10% of population.
 epithelium lining the oral region of gingiva is keratinized
st sq epithelium.
 Free gingival groove is represented as a shallow V
shaped notch on surface corresponding to a heavy
epithelial ridge.

158.  Stippling on the attached gingiva is reflected by
alternate rounded protuberances and depressions on
the surface.
 The depression corresponds to center of heavy
epithelial ridges.
 The epithelium and C.T interface is irregular with
numerous long narrow rete ridges interdigitating with
long C.T papillae.
 This extensive interdigitation increases the strength to
withstand the masticatory stresses.

159.  lamina propria of gingiva consists of dense bundles of
collagen fibers, which maintains the integrity of the
supporting apparatus of the tooth. These fibers are
referred to as the secondary fibers of periodontal
ligament or gingival ligament or gingival fibers of
periodontal ligament.
 Few elastic fibers and oxytalan fibers are also present in
the gingiva.

160. MELANIN PIGMENT IS PRESENT IN THE
GINGIVAL EPITH.
Elaborated by melanocytes (basal layer).
Can be studied by dopa reaction or silver
staining techniques.
The number of melanocytes is constant
(no difference in their no. in blacks or
whites).

161.  Melanin pigment is present in the gingival epith.
 Elaborated by melanocytes (basal layer)
 Can be studied by dopa reaction or silver staining
techniques.
 The number of melanocytes is constant (no difference in
their no. in blacks or whites).

162. Pigmented gingiva
Attached gingiva

163. Melanin pigment

164. 1. Dentogingival group .
2. Alveologingival group.
3. Circular group.
4. Dentoperiosteal group.
5. Transseptal group (interdental lig.).
6. Circular
7. Interdental
8. Semicircular
9. Longitudinal
10. vertical
GINGIVAL LIGAMENTS

165. DENTOGINGIVAL FIBRES

166. DENTOPERIOSTEAL FIBRES

167. ALVEOGINGIVAL FIBRES

168. CIRCULAR AND SEMICIRCULAR FIBRES

169. TRANSSEPTAL FIBRES

170. TRANSGINGIVAL AND INTERGINGIVAL FIBRES

171. INTERPAPILLARY FIBRES INTERDENTAL

172. GINGIVAL LIGAMENT
.Dentoperios. gr
.Circular gr
.Alveolog. gr
.Dentog. gr

174. • Nonkeratinized stratified
squamous epith.
• Thinner than epith. of
gingiva.
• Lacks epithelial ridges
i.e. has smooth interface
with lamina propria.
• Continuous with gingival
epith. & attachement
epith.
• All three epithelia have a
continuous basal lamina
GINGIVAL SULCUS

175. Gingival margin
Free gingiva
sulcus
gingiva
Gingival stippling
Free
gingival
groove
attached
Dentin
Space of
enamel
Sulcular epithelium
Junctional epithelium
cementum
dentino
gingival
fibers
GINGIVA
– Micro-Anatomy Gingival

176. JUNCTIONAL EPITHELIUM
 The part of the gingival epithelium that is attached to
the cervical part of the tooth (forms junction between
the tooth and the gingiva)
 It is st sq epithelium composed of flattened cells which
are arranged parallel to the tooth surface.
 Traingular shape with 15-30 cell layer thickness at the
cervical portion and 3-4 cell layer at the apical margin.

177.  Less desmosomal
junction and more
intercellular spaces
(helps in migration of
PMNLs into epithelium
and sulcus.
 The epithelium and C.T
interface is flat.
 Basal lamina is present
on both sides.

178. HARD PALATE
• it is immovable.
• Pink in color.
• The lamina propria is thicker anteriorly and has
numerous long papillae.
• Various regions can be distinguished because
of varying structures of the submucous layer.

180.  These regions are:
 Gingival region (adjacent to the teeth).
1. palatine raphe (extending from incisive papilla
posteriorly).
2. Anterolateral area (fatty zone)between the raphe and
gingiva.
 Posterolateral area (glandular zone) between the
raphe and gingiva.
 The peripheral zones (palatine gingiva) do
not have a submucosa (identical with the
gingiva and palatine raphae)

181.  incissive papilla: oval prominence at the extreme
anterior region of the palate
 Palatine rugae: irregular transverse ridges radiating
outwards from the raphae in the anterior region
 Fovia palatina: elongated depression in post part of
palate on sither side of midline

182. HARD PALATE MACRO-ANATOMY
incisive
papilla
median
palatine
soft
palate
uvula
raphe
palatine
gingiva
palatine
rugae
antero-
lateral (fatty
Zone)
postero-
lateral
(glandular
(zone

183. HISTOLOGY
 the epithelium is keratinized stratified squamous
epithelium with long regular reteridges interdigitating
with C.T papillae.
 To bear masticatory stresses, the cells show more
dense tonofilaments, increased number and length of
desmosomes.
 Lamina propria is dense (thicker in anterior compared to
posterior)

184.  SUBMUCOSA:
 Absent in peripheral zone of palate ( gingival zone and
midpalatine raphae)
 Thicker in posterior region than anterior region
 Anterior part is filled with adipose tissue (FATTY ZONE)
 Posterior part with mucous glands (GLANDULAR
ZONE)

185.  dense bundles of collagen fibers divide the submucosa
into compartments and are arranged at right angle to
surface.
 The wedge shaped area where the alveolar process
joins to the horizontal plate of hard palate contains loose
C.T
 Rugae and incissive papilla are composed of dense C.T.

186. Palate : dense lamina propria with fat in some regions of the
submucosa

187. Submucosa
Fatty zone
Glandular zone
Epithelial rete pegs
are regular, tall and
numerous
Mucosa

188. VERMILLION ZONE OF LIP
 The transitional zone between the skin of the lip and the
mucous membrane of the lip is the red zone or
vermillion zone.
 The skin on outer surface of lip is covered by a
moderately thick keratinized epithelium.
 C.T papillae are few and short
 Many sebaceous glands, hair follicles and sweat glands
are present

189.  the transitional region is characterised by a thicker but
mildly keratinized epithelium and numerous densely
arranged long papillae of the lamina propria, reaching
deep into the epithelium and carrying large capillary
loops. (red color to lips)
 The labial mucosa is lined by nonkeratinized epithelium
and C.T shows minor salivary glands.
 The central most region of lip shows orbicularis oris
muscle.

191. LINING MUCOSA
 The epithelium of lining mucosa is thicker and is non -
keratinized. The surface is thus flexible and is able to
withstand stretching.
 The interface with connective tissue is relatively smooth,
although slender connective tissue papillae often
penetrate into the epithelium.
 The lamina propria is generally thicker than in
masticatory mucosa and contains fewer collagen fibers,
which follow a more irregular course between anchoring
points. Thus, the mucosa can be stretched to a certain
extent before these fibers become taut and limit further
distention.

192.  Associated with the collagen fibers are elastic fibers
that tend to control the extensibility of the mucosa.
 Where lining mucosa covers muscle, it is attached
by a mixture of collagen and elastic fibers.
 As the mucosa becomes slack during masticatory
movements, the elastic fibers retract the mucosa
toward the muscle and so prevent it from bulging
between the teeth and being bitten.

193. Soft palate –
 Mucous membrane on oral surface is highly
vascularized (well developed capillary network) and
reddish in color
 Nonkeratinized stratified squamous epithelium
 C.T is thick with numerous short papillae
 Elastic fibres forming an elastic lamina
 Submucosa has diffuse tissue containing numerous
minor salivary glands

194. Labial and buccal mucosa-
 Epithelium: Very thick (500 μ m), non - keratinized stratified
squamous epithelium
 lamina propria: short irregular papillae, dense fibrous
connective tissue containing collagen and elastic fibers
 Rich vascular supply
 Submucosa- Dense collagenous connective tissue with fat,
mixed minor salivary glands
 Dense collagenous connective tissue limits the mobility of the
mucous membrane, holding it to musculature and preventing
its elevation into folds. This prevents the mucous membrane
of lips and cheeks from lodging between the the biting
surfaces of teeth during mastication.

195.  The submucosa connects the lamina propria to the
thin fascia of the muscles
 Lips : orbicularis oris and Cheek: Buccinator
 The cheek, lateral to the corner of the mouth, may
contain isolated sebaceous glands called Fordyce
spots.

196. Ventral surface of tongue –
 Mucous membrane is smooth and relatively thin
 Thin, non - keratinized, stratified squamous
epithelium
 Lamina propria is thin with numerous short papillae
and some elastic fibers
 Few minor salivary glands
 Capillary network in subpapillary layer
 Reticular layer relatively avascular
 Submucosa- thin and irregular, may contain fat and
small vessels
 If absent, mucosa is bound to connective tissue
surrounding tongue musculature

197. Floor of mouth-
 Mucous membrane is thin and loosely attached to the
underlying structures to allow for the free mobility of the
tongue.
 Epithelium: Very thin (100 μ m), non - keratinized
stratified squamous epithelium
 Lamina propria: Short papillae, some elastic fibers
 Extensive vascular supply with short anastomosing
capillary loops
 Submucosa- loose fibrous connective tissue containing
fat and minor salivary glands

198. Alveolar mucosa-
 Epithelium: Thin, non – keratinized stratified
squamous epithelium
 Lamina propria: Short papillae, connective tissue
containing many elastic fibers
 Capillary loops close to the surface supplied by
vessels running superficial to the periosteum
 Submucosa- loose connective tissue containing
thick elastic fibers, minor salivary glands

199. Vestibular fornix
 The mucosa is loosely connected to the underlying
structures, and so the necessary movements of the
lips and cheeks are permitted.
 The median and lateral labial frenula are folds of
the mucous membrane containing loose C.T.
 No muscle fibers are found in these folds.

200. SPECIALIZED MUCOSA

201. DORSAL SURFACE OF TONGUE
TONGUE
ROOT APEX BODY
DORSUM INFERIOR
•ORAL PART
•PHARYNGEAL PART

203. ORAL(PRESULCAL) PART
 located in floor of oral cavity
 Apex touching the incisor teeth, a
margin in contact with the gums
and teeth and a superior surface
related to hard and soft palate
 On each side in front of
palatoglossal arch there are four
or five vertical folds - foliate
papillae
 Dorsal mucosa - covered by
filiform, fungiform and
circumvallate papillae
 Inferior surface – lingual
frenulum, lingual vein, plica
fimbriata

204. PHARYNGEAL(POSTSULCAL) PART
 Behind palatoglossal arches
and sulcus terminalis.
 No papillae
 Lymphoid follicles –lingual
tonsil
 Connected to epiglottis by
three folds of mucous
membrane
-median glossoepiglottic
fold and
-right and left lateral
glossoepiglottic fold

205.  Dorsal surface has both a masticatory and a
specialized type of mucosa present
 Masticatory is orthokeratinized stratified squamous
epithelium; generally covers surface
 Specialized found on lingual papillae has both
ortho- and para- keratinized epithelium

206. LINGUAL PAPILLAE
 Projections of mucosa covering dorsal surface
 Limited to presulcal part
 Four types -
Filiform
Fungiform
Foliate
Circumvallate

207. FILIFORM PAPILLAE
 minute conical or cylindrical projections
 Cover most of the presulcal dorsal area
 Most abundant
 Cone shaped structures with a core of CT covered
by a thick keratinised epithelium
 No taste buds
 Appear to increase the friction between the tongue
and food

208. FUNGIFORM PAPILLAE
 Single fungiform papillae
scattered between numerous
filiform papillae at tip of tongue
 Appear red high vascular CT
core visible through a thin
nonkeratinised covering
epithelium
 Larger, rounded and deep red
in color
 Each usually bears one or
more taste buds on its apical
surface
 Blue arrow – filiform papillae
 Red arrow – fungiform papillae

209. LARGE PAPILLAE – FUNGIFORM PAPILLAE
SMALL PAPILLAE – FILIFORM PAPILLAE

210. FOLIATE PAPILLAE
 Leaf - like
 4-11 parallel ridges that
alternate with deep
grooves in mucos
 Taste buds in
epithelium of lateral
walls of ridges
 Located on extreme
postero –lateral surface
of tongue
 Mistaken for tumors or
inflammatory diseases
 Bilaterally symmetrical

211. CIRCUMVALLATE PAPILLAE
 Largest
 Least in number,8-12
 Forms a V-shaped row
immediately in front of sulcus
terminalis
 Large structures surrounded by
deep circular groove
 Ducts of von Ebner glands open
into these grooves
 Have a CT core covered superiorly
by keratinised epithelium
 Epithelium of lateral walls is non
keratinised, contains taste buds
 Blue arrow – circumvallate
papillae
 A – trench
 Green arrow – taste buds

212. STRUCTURE OF TASTE
BUD
 Barrel shaped structure
composed of 30-80 spindle
shaped cells
 80µm in height and 40µm thick
 Cells separated from underlying
CT by basement membrane
 Apically , terminates just below
the epithelial surface in a taste
pit that communicates with
surface through a taste pore
 3 types of cells:
 Type I- light, most common
 Type II- dark, contain vesicles,
adj to intra epithelial nerves
 Type III-intermediate

213. TASTE DISCRIMINATION
 Mainly four types -
- salty
- sweet
- sour
- bitter
 metallic and umami
(monosodium glutamate)
 Classic theory of taste –
perception of taste reserved
to specific areas
 Modern theory – perception
possible in whole surface

214. SWEET Tip of the
tongue
Fungiform
papillae
Chorda
tympani
SALT Lateral border
of the tongue
Fungiform
papillae
Chorda
tympani
SOUR Palate and
posterior part
of tongue
Foliate
papillae
Glosso-
pharyngeal
BITTER Palate and
posterior part
of tongue
Circum-vallate
papillae
Glosso-
pharyngeal

216.  FUNCTIONS OF TONGUE

Prehension And Ingestion
Suckling
Swallowing
Perception
Phonation
Respiration
Jaw development
Symbolic functions

217. JUNCTIONS IN ORAL MUCOSA
 Mucocutaneous junction
 Mucogingival junction
 Dentogingival junction

218. MUCOCUTANEOUS JUNCTION
 The skin with hair follicles and sebaceous and
sweat glands is continuous with the oral mucosa at
the lips
 Epithelium keratinised, with thin long CT papillae
containing capillary loops
 This brings blood close to the surface and gives
strong red coloration called red /vermillion zone
 The line separating vermillion zone from skin of lip
called vermillion border.
 In young persons, this border demarcated sharply,
later becomes diffuse

219.  Vermillion zone lacks salivary glands, contains only
a few sebaceous glands, it tends to dry out,
becomes cracked and sore in cold weather
 Between vermillion zone and thicker non
keratinised labial mucosa is an intermediate zone
covered by parakeratinised epithelium
 In infants this region is thickened and more
opalescent: suckling pa

220. MUCOGINGIVAL JUNCTION
 Although masticatory mucosa meets lining mucosa
at more than 1 site, most abrupt is between
attached gingiva and alveolar mucosa
 Identified clinically by indentation called
mucogingival groove and by change from bright
pink of alveolar mucosa to paler pink of gingiva
 Epithelium of attached gingiva is keratinised or
parakeratinised
 Lamina propria contains numerous coarse collagen
bundles attaching tissue to periosteum; reflected
clinically as stippling

221.  The structure of mucosa changes at mucogingival
junction where alveolar mucosa has thicker
nonkeratinised epithelium over loose lamina propria
with numerous elastic fibres extending into thick
submucosa

222. DENTOGINGIVAL JUNCTION
 Region where oral mucosa meets surface of tooth
 Important because it represents a potential
weakness in the otherwise continuous epithelial
lining
 Principal seal between epithelium and enamel
 In germ free animals and in strictly healthy plaque
free gingivae, sulcus is absent and gingival margin
corresponds to coronal extent of junctional
epithelium
 In avg human mouth, gingival sulcus has a depth of
0.5-3 m with an avg of 1.8 mm

223. THE GINGIVAL SULCUS
is an area of potential space between
a tooth and the surrounding gingival
tissue.
It is lined by two entities:
-Apically by the gingival fibers of
connective tissue attachment .
_Coronally by free gingival margin .

224. THE GINGIVAL SULCUS
Under normal conditions the depth
of the sulcus is variable.45% of all
measured sulci are below 0.5 mm
,the average sulcus is 1.8mm
the shallower sulcus is the more
likely that the gingival margin is
not inflamed

226. THE SULCULAR EPITHELIUM
Its stratified squamous
epithelium ,non keratinized .
Para keratinized that is
continuous with the oral
epithelium and lines the
lateral surface of the sulcus .
Its lacks epithelial ridges so
forms a smooth contact with
lamina properia

227. THE SULCULAR
EPITHELIUM
Apically it overlaps the
coronal border of the
junctional epithelium
this epithelium shares many
of the characteristics of oral
including good
epithelium
resistance to
forces and
mechanical
relative
impermeability to fluid and
cells

229. THE JUNCTIONAL EPITHELIUM
Its the stratified non keratinizing
epithelium that surround the tooth like a
collar.
its attached by one broad surface to the
tooth and by the other to the gingival
connective tissue
The junctional epithelium has two
basal lamina:
oOne that faces the tooth (internal basal
lamina )
oThe other faces connective tissue
(external basal lamina)

230. THE JUNCTIONAL EPITHELIUM
shedding
The desquamative
surface of the junctional epithelium
is located at its coronal end which
also forms the bottom of the
gingival sulcus
The junctional epithelium is more
permeable than
epithelium It
perferential route for the passage
oral or sulcular
serves as the
of
bacterial products from the sulcus in
to connective tissue into the sulcus

232. THE SULCULAR EPITHELIUM THE JUNCTION EPITHELIUM
1. It is continuous with the oral
epithelium and lines the lateral
surface of the sulcus .
2. It characterized by good
resistance to mechanical forces
and relative impermeability to
fluid and cells
1. It is epithelium that surround
the tooth like acollar .
2. It is more permeable than oral or
sulcular epithelium It serves as
the perferential route for the
passage of bacterial products from
the sulcus in to connective tissue
and fluid and cells from C.T into
the sulcus

233. DEVELOPMENT OF THE JUNCTIOANAL EPITHELIUM
As the erupting tooth approaches the
overlying epithelium, the external
enamel
cells of the reduced
epithelium proliferate, causing the
epithelial covering of the enamel to
thicken.

234. DEVELOPMENT OF THE JUNCTIOANAL EPITHELIUM
 Proliferation of the externel cells
of the reduced enamel epithelium
begins around the cusp tips and
slowly progresses toward the
cervix of the tooth

235. DEVELOPMENT OF THE JUNCTIOANAL EPITHELIUM
proliferating cells eventually displace
any remaining reduced ameloblasts, thus
replacing the relatively inert reduced
with an epithelial
enamel epithelium
collar of cells with a high turnover
rate. This collar of cells with a high
turnover rate is the early junctional
epithelium.
Eventually, the entire reduced enamel
epithelium will become replaced by
junctional epithelium.

237. DEVELOPMENT OF THE JUNCTIOANAL EPITHELIUM
After accomplishing of amelogenesis
 (protective stage) the ameloblast secrete or leave
structure less material on enamel surface primary
enamel cuticle.
The enamel organ becomes reduced in thickness
(reduced enamel epithelium ) and function as
aprotection against contact with connective tissue ,to
inhibit cementum deposition or enamel resorption
 The reduced enamel epi thelium
 consists of two layers
1the reduced ameloblast
2 remnant of the dental organ

238. DEVELOPMENT OF THE JUNCTIOANAL EPITHELIUM
The ameloblast develop hemidesmosomes
to attach the reduced enamel epithelium to
the surface of the enamel at the time of
eruption the reduced enamel
enzymes
secrete desmolytic
degenerating of the of the
epithelium
causing
c.t present
between it and the oral mucosa (desmolytic
stage of amelo blasts)
The outer the reduced enamel
layer of
and the cells of the oral
epithelium
epithelium proliferate into the degenerated
c.t. to form amass of cells over the erupting
tooth the epithelialplug.

240. DEVELOPMENT OF THE JUNCTIOANAL EPITHELIUM
Cell death inth middle portion of plug cause formation of epithelial lined canal
through which tooth will eruptwith out hemorrhage
Once the tip of the crown appear in the oral cavity reduced enamel epithelium will be
called primary attachedepithelium
groove present between the tooth and the gingiva is called
And the the shallow
GINGIVAL SULCUS
The cells of primary attached epithelium (PAE) originate from reduced enamel
epithelium and attached to tooth by primary enamel cuticle
When primary attachment epithelium is replaced by oral epithelium its called
secondary attached epithelium that attaches by secondary enamel cuticle.

241. Primary enamelcuticle Secondary enamelcuticle
1. Binds primary attached epithelium
to the enamelsurface
2. It is formed initially at the
protectivestage
1. Binds secondary attached
epithelium to the enamelsurface
2. It is formed finally when theteeth
erupt
Primary attachedepi. Secondary attachedepi.
1. originate from reducedenamel
epithelium
2. attached to tooth by primary
enamel cuticle
1. It is Primary attachment
epithelium replaced by oral
epithelium
2. attached by secondary enamel
cuticle

242. SHIFT OF THE DENTO GINGIVAL JUNCTION
 The dentogingival junction is an anatomical
and functional interface between the gingiva
and the toothstructure.
 Dento gingival junction is the region where
the tooth is attached to gingival and is form
as soonas the tootherupts in theoral cavity.
 It provides attachment of the gingiva tothe
enamel surface viahemidesmosomes
 with time the position of the gingiva of the
surfacechange

243. SHIFT OF THE DENTO GINGIVAL JUNCTION
 Components
1. Epithelial component is derived from
reduced dental (enamel) epithelium
and oral epithelium.
2. The connective tissue component is
derived from the lamina propria of the
oral mucosa.
 The attachment of the functional
epithelium to the tooth is reinforced with
the gingival fibers, which brace the gingival
against the toothsurface.

244. DENTO GINGIVAL JUNCTION

245. SHIFT OF THE DENTO GINGIVAL JUNCTION
almost entire enamel is covered by
epithelium when the tip of the enamel
first emerge through the mucous
membrane of the oral cavity.
the eruption of teeth continuous until it
reach theplan of occlusion.
 the firmness strength of the dentino
junction beacause of connective
attachment of epithelium to
gingival
tissue
enamel is not week as the crown
continuouson totheoral cavity
the attachment separate from theenamel
surfacegradually

247. SHIFT OF THE DENTO GINGIVAL JUNCTION
when the tip of the enamel first emerge through the mucous membrane of
theoral cavity . one third toone fourth of enamel is still covered by thegingiva
The actual movement of teeth towards occlusal plane called acitve
eruption
The separation of primary attached epithelium from the enamel
surface called passiveeruption

248. THE SHIFT OF DENTINO GINGIVAL
JUNCTION INVOLVE
 Firststage
 Occur in the primary teeth till one year
before shedding in the permanent teeth
20_30.
 the bottom of the sulcus present on the
enamel and the apical end of the AE on
the cement enameljunction.
 Clinical crown is less than anatomical
crown.

249. THE SHIFT OF DENTINO GINGIVAL
JUNCTION INVOLVE
 Second stage
 Occur till ageof the 40 oreven later.
 The bottom of the sulcus still present
on the enamel and the apical end of the
AE oncementum.
 the clinical crown is less than
anatomical crown.

250. THE SHIFT OF DENTINO GINGIVAL
JUNCTION INVOLVE
 Third stage
 It is unhealthycondition.
 The bottom of the sulcus present at the
CEJ and the apical end at cementum.
 The clinical crown equal to the
anatomical crown.

251. THE SHIFT OF DENTINO GINGIVAL
JUNCTION INVOLVE
 Fourthstage
 It is unhealthycondition.
 From 60 years later.
and apical
 The bottom of the sulcucs
end on thecementum.
than
 The clinical crown is longer
anatomical crown

252. DEVELOPMENT OF ORAL MUCOSA
 Epithelium of the oral cavity is derived from ectoderm
and endoderm
 Anterior part of oral cavity is lined by epithelium derived
from ectoderm
 The structures that develop from branchial arches have
their epithelium derived from the endoderm
 These include- tongue, epiglottis and pharynx
 Originates from mesenchyme (embryonic tissue formed
by mesenchymal cells)- MESODERM

253.  The vestibular lamina separates from the primary
epithelial band at about 6 weeks
 Degeneration of the cells in the central part of this
process leads to the formation of labial and buccal
sulcus and the delineation of lips and cheeks from
the alveolar mucosa
 By 13- 20 weeks differences between keratinised
and non keratinised mucosa becomes apparent

254.  Lingual papillae appear early at about 7th week
 Circumvallate and folliate papillae appear earlier
than filiform papillae
 Can be recognized by 10-12 weeks
 In the lamina propria reticular fibers are the first to
appear (6-8 weeks)
 Followed by collagen fibers (8-12 weeks)
 Elastic fibres appear by 17-20 weeks

255. AGE CHANGES
 Smoother & dryer surface
 Histologically epithelium thinner
 Smoothing of the epithelium- connective interface
due to flattening of epithelial ridges
 Dorsum of tongue may show a reduction in the
number filiform papillae

256.  Langerhans cells with age
 Vascular changes maybe prominent with
development of varicosities
 In elderly persons- nodular varicose veins on the
undersurface of the tongue

257. Ventral surface of tongue in an elderly patient showing varicosities

258.  In the lamina propria - decreased cellularity
 Increased amount of collagen
 Sebaceous glands of lips and cheeks increase with
age
 Minor salivary glands show considerable atrophy
 Elderly patients post menopausal women – dryness
of mouth burning sensations and abnormal taste

259. CLINICAL CONSIDERATION
 The basic considerations in oral mucosa are
variation in tissue colour, dryness, smoothness or
firmness and bleeding tendency of gingiva
 Periodontal pocket: It is a pathologically deepened
gingival sulcus as a response to plaque toxins and
subsequent immunologic response.
 Restorative dentistry: In young patients, when the
clinical crown is smaller than the anatomic crown, it
is difficult to prepare a tooth for an abutment or
crown. The restoration may require replacement
when the crown is fully exposed

260.  Gingival recession: May result in cemental /root
caries and sensitivity of the exposed dentin
 Keratinisation of gingiva: Can be achieved by
massage or brushing thus helping in stimulation
and minimising plaque accumulation
 Discoloration of gingiva: Metal poisoning by lead or
bismuth causes characteristic discoloration.
 Changes of tongue: In scarlet fever, atrophy of
lingual mucosa causes peculiar redness of
Strawberry tongue. Systemic diseases such as
vitamin deficiencies lead to typical changes as
Magenta tongue and beefy red tongue

261. REFERENCES
 Ten Cates oral histology, development, structure
and function – 7th edition
 Oral anatomy histology embryology – 3rd edition -
Berkovitz , Holland , Moxham
 Orbans oral histology and embryology-12th edition