different clinical anatomies and histology of oral cavity

2.  DEFINITION
 FUNCTIONS
 ORGANIZATION
 CLINICAL FEATURES
 ORAL EPITHELIUM
 BLOOD SUPPLY AND NERVE SUPPLY

3.  Extends from the lips to the
oropharyngeal isthmus
 The oropharyngeal isthmus: Is
the junction of mouth and
pharynx.
 Is bounded:
1- Above by the soft palate and the
palatoglossal folds
2- Below by the dorsum of the
tongue
 Subdivided into Vestibule &
Oral cavity proper

4.  Slit like space between the
cheeks and the gums
 Communicates with the
exterior through the oral
fissure
 When the jaws are closed,
communicates with the oral
cavity proper behind the 3rd
molar tooth on each side
 Superiorly and inferiorly
limited by the reflection of
mucous membrane from lips
and cheek onto the gums

5.  The lateral wall of the
vestibule is formed by the
cheek
 The cheek is composed of
Buccinators muscle,
covered laterally by the skin
& medially by the mucous
membrane
 A small papilla on the
mucosa opposite the upper
2nd molar tooth marks the
opening of the duct of the
parotid gland

6.  It is the cavity within the
alveolar margins of the
maxillae and the mandible
 Its Roof is formed by the
hard palate anteriorly and
the soft palate posteriorly
 Its Floor is formed by the
mylohyoid muscle. The
anterior 2/3rd of the tongue
lies on the floor.
hard
soft
palate
mylohyoid

7. ORAL MUCOSA
Mucous Membrane: Moist lining of the gastrointestinal tract,
nasal passages and other body cavities that communicate with the
exterior
In the oral cavity the lining is called as Oral Mucous Membrane
or Oral Mucosa

8. FUNCTIONS OF THE ORAL MUCOSA
1. Protection: Barrier for mechanical trauma and microbiological
insults
2. Sensation: Temperature (heat and cold), touch, pain, taste
buds, thirst , reflexes such as swallowing, etching, gagging and
salivating
3. Secretion: Salivary secretion
4. Thermal regulation: Important in dogs not in humans

9. CLASSIFICATION OF ORAL MUCOSA: FUNCTION

10. 10
MASTICATORY MUCOSA

11. 11
MASTICATORY MUCOSA

12. 12
LINING MUCOSA

13. 13
SPECIALIZED MUCOSA

14. CLINICAL FEATURES OF ORAL MUCOSA
1. Separated from the skin by vermillion zone of the lips which is
more deeply colored than rest of the oral mucosa
2. Factors affecting color of the oral mucosa:
a. Concentration and state of dilation of the blood vessels in
underlying connective tissue
b. Thickness of the epithelium
c. Degree of keratinization
d. Amount of melanin pigmentation
Clinically, color of oral mucosa is very important. For example,
inflamed oral tissues appear red rather than the normal pale
pink

15. 15
NORMAL VS INFLAMED TISSUES

16. LINEA ALBA
 The linea alba (Latin for white
line)to describe a horizontal
streak on the inner surface of the
cheek level with the biting plane.
 It usually extends from the
commissure to the posterior teeth
and can extend to the inner lip
mucosa and corners of the
mouth.
 most likely associated with
pressure, frictional irritation, or
sucking trauma from the facial
surfaces of the teeth.

17. STRUCTURE OF ORAL MUCOSA
1. Overlying oral epithelium
1. Underlying connective tissue
(lamina propria and sub mucosa)
In skin called epidermis and dermis
The oral mucosa is of stratified
squamous type.

18. 18
The oral epithelium is keratinized or non-keratinized stratified squamous epithelium
The interface between epithelium and connective tissue is comprised of a
Structure less layer called basement membrane
This interface is irregular and is composed of downward projections of epithelium
called rete ridges or rete pegs, and upward projection of connective tissue termed as
connective tissue papillae
A: Epithelium
B: Connective tissue
C: Salivary gland
A: Startum basale
B: Startum spinosum
C: Startum superficiale

19. Junction between oral epithelium and lamina propria is more obvious than that between
lamina propria and sub mucosa
No muscularis mucosae layer seen in oral mucosa
Loose fat and glandular tissue with blood vessels and nerves seen underneath oral mucosa
from underneath bone or muscle layer - this layer is termed SUBMUCOSA – provides flexibility
In gingiva and hard palate, no sub mucosa is seen and the lamina propria is directly
attached to the periosteum of the underlying bone which provides firm, inelastic attachment –this is
called ORAL MUCOPERIOSTEUM

20. BASEMENT MEMBRANE
Interface between connective
tissue and epithelium appears
thick and it includes reticular
fibres.
 1-4 micrometre wide and cell
free.
Ultra structurally , basement
membrane is called Basal
Lamina.
Basal lamina is made up of clear
zone called Lamina Lucida just
below the epithelial cells.
A dark zone beyond lamina
lucida adjacent to the
connective tissue is called
Lamina Densa.

22. LAMINA PROPRIA
Superficial papillary layer (associated with rete
ridges) and deeper reticular layer
(between papillary layer and deeper structures)
Reticular refers to the netlike arrangement of
collagen fibers (nothing to do with reticulin
fibers)
Papillary layer has thin and loose collagen
fibers with many capillary loops
Reticular layer has collagen fibers arranged in
thick bundles that are parallel to surface
Lamina propria also contains various cells,
blood vessels, nerves and fibers
(collagen and elastic) embedded in an
amorphous ground substance

23. SUBMUCOSA
Consists of connective tissue of
varying thickness and density.
It attaches mucous membrane to
underlying structures.
Glands , nerves , blood vessels
and also adipose tissue are
present.

24. STRATUM BASALE
 Basal layer is made up of single layer of
cuboidal cells that undergo mitosis.
 New cells are generated in basal layer.
 The basal cell and parabasal spinous cells are
called Stratum Germinativum , but only
basal cells divide.
 Basal cells are made up of two populations:
serrated and heavily packed with
tonofilaments.
 And the other is non serrated and is
composed of slowly serrated stem cells.
 Specialized structures called Hemi
desmosomes which abut on the basal lamina
are found on the basal surfaces.
 The lateral border of adjacent basal cells are
closely apposed and connected of
Desmosomes.

25. STRATUM SPINOSUM
 Spinous cells are irregularly polyhedral
and larger than basal cells.
 Cells are joined by intercellular bridges.
 electron microscopy shows that the
intercellular bridges are desmosomes and
tonofibrils are bundles of tonofilaments.
 The tonofilament network and
desmosomes appear to make up tensile
supporting system for the epithelium.
 The spiny appearance of spinous layer is
due to the shrinkage of cells during tissue
preparation causing them to separate at
points where the desmosomes do not
attach them.
 The spinous layer resemble a Cocklebur
or sticker that has each spine ending at a
desmosome.

26. STRATUM GRANULOSUM
 This layer contains flatter and wider
cells.
 This layer is named for basophilic
keratohyalin granule layer that it
contains.
 Nuclei shows degeneration and
pyknosis.
 The lamellar granule , a small organelle
also known as keratinosome , Odland
body or membrane coating granule ,
forms in upper spinous and granular
layer.
 In non keratinizing oral epithelium a
small granule forms.
 These granules are elongated ,and
lamellar in keratinized & circular &
amorphous in nonkeratinized
epithelium.

27. STRATUM CORNEUM
Other name is cornified layer
and horny layer.
Is made up of keratinized
squamae which are larger and
flatter than the granular cells.
All nuclei and ribosomes and
mitochondria have disappeared.
The cells are densely packed with
filaments in this nonfibrous
interfilamentous matrix protein ,
filaggrin.

28. NONKERATINIZED EPITHELIUM
They do not produce a
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 larger than
cells of larger than cells of
stratum spinosum.
There is no stratum
granulosum / nor there is
stratum corneum.

29. 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

30.  Epidermal/epithelial cells
that secrete keratin
 Shows intermediate filament
protein
 Undergoes: cell division,
maturation and finally
desquamate.
 Increase in volume: from
basal to superficial.
 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 water loss

31. Melanocytes are melanin-
producing cells located in the
bottom layer (the stratum
basale).
 embryological neural crest and
migrate into epithelium
 establishes contact through
dendritic processes
 appear clear in H and E stains,
hence called as clear cells or
dendritic cells.
Function: Melanin production

32. 
Langerhans cells are dendritic cells
(antigen-presenting immune cells)
of the skin and mucosa, and
contain large granules called
Birbeck granules.
 Hematopoietic in origin.
 Free of melanin, do not give
dopa reaction.
 presents antigen to T cells.
Function:
Contact hypersensitivity
Anti tumour immunity
Graft rejection

33.  Merkel cells are found in the
stratum basale.
 Specialized neural pressure-
sensitive receptor cell.
 Commonly seen in masticatory
mucosa.
 Non dendritic
 Migrate from the neural crest.

34. JUNCTION BETWEEN EPITHELIUM & LAMINA PROPRIA

35. CELL TYPES IN THE LAMINA PROPRIA OF ORAL MUCOSA

36. FIBRES AND GROUND SUBSTANCES
The intercellular matrix of the lamina propria consists of 2 major
types of fibres i.e. collagen and elastin.
 Together with fibronectin embedded in ground substance
composed of glycosaminoglycan's and serum derived proteins.
 Collagen: lamina propria is type I and type III , IV and VII in
basal lamina. Type V in inflamed tissue.
 Elastic fibres: consists of 2 protein components
 Ground substance: it consists of protein-carbohydrate
complexes permeated by tissue fluid.
Chemically , these complexes can be sub divided into:
proteoglycans and glycoproteins.

37. BLOOD SUPPLY AND NERVE SUPPLY
Blood supply of gingiva is derived chiefly from the branches of
alveolar arteries that pass upward through interdental septa.
Gingiva is well innervated . Different types of nerve endings can
be observed , such as the Meissner or Krause corpuscles , end
bulbs , loops or fine fibres that enter epithelium as
“ultratterminal” fibres.
Blood supply to the gingiva: Derived from periosteal vessels in the
periosteum of the alveolar process
Blood supply to the dentogingival junction: Continuation of
interalveolar arteries
Nerve supply to the gingiva: terminal branches of periodontal
nerve fibers and by branches of the infraorbital and palatine, or
lingual, mental, and buccal nerves

39. Components of Oral Epithelium
LINING MUCOSA:
Stratum Basale: Basal cell layer comprised of cuboidal cells.
Progenitor cells that divide and provide new cells by mitotic division
that migrate to the surface to replace cells that are shed.
Stratum Spinosum (or intermedium): Cells are oval and
represent bulk of the epithelium.
Stratum Superficiale: Cells are flat and contain small oval nuclei
that are continuously shed.

40. 40
JUNCTIONAL EPITHELIUM
The epithelium that is attached to the tooth (enamel or sometimes cementum)
surface
continuous with sulcular epithelium
Derived from reduced enamel epithelium of the tooth germ
Junctional epithelium consists of flat cells aligned parallel to the tooth surface
increasing in thickness from the apex to the crown
Attached to enamel by internal basal lamina and to the connective tissue by
external
basal lamina. Hemidesmosomes are present in both basal laminas.

41. EPITHELIAL CELL TURNOVER IN GINGIVA
Similar to all other epithelia, the deeper
cells adjacent to the connective tissue
undergo cell division to replenish those
lost at the surface
High rate of cell division
Migrate about 2 to 3 cell layers from the
tooth surface and then join a main migratory
route in a coronal direction, parallel to tooth
surface, to be desquamated into the
gingival sulcus.
Key point: Junctional epithelium readily
regenerates from the sulcular epithelium
or oral epithelium if it is damaged or
surgically excised
Connective tissue normally contains plenty
of neutrophils which is different
than the normal oral mucosa

42. DENTOGINGIVAL FIBRES

43. DENTOPERIOSTEAL FIBRES

44. ALVEOGINGIVAL FIBRES

45. CIRCULAR AND SEMICIRCULAR FIBRES

46. TRANSSEPTAL FIBRES

47. TRANSGINGIVAL AND INTERGINGIVAL FIBRES

48. INTERPAPILLARY FIBRES

49. PERIOSTEOGINGIVAL FIBRES AND INTERCIRCULAR FIBRES

50. REFERENCE :-
TEN CATE’S – ORAL HISTOLOGY ,
DEVELOPMENT STRUCTURE AND FUNCTION
(7TH EDITION)
ORBAN’S ORAL HISTOLOGY AND
EMBRYOLOGY
( 11TH EDITION)