Objectives:At the end of this subject students should know thoroughly: 1- The definition & function of oral mucous membrane.2- The classification of oral mucous membrane.3- The histological structure of the mucous membrane. 4- The differences between the two different types of the oral epithelium.5- Keratinocytes and non keratinocytes.6- The macro & micro-anatomy of the gingival.7- The macro & micro-anatomy of the hard palate.8- The different types of lining mucosa.9- The specialized mucosa and the different types of the papillae.10- Dento-gingival junction (Histology and Histogenesis)

Oral mucous membrane

Gingiva

Alveolar mucosa

Vestibular fornix

Labial mucosa

Cheek mucosa

Hard palate

Dorsal surface of

the tongue

Ventral surface of the tongue

Floor of mouth

Macro-anatomy of the gingiva

- It Extends along the cervical level facially and lingually.

- It is freely movable.

-It tapers to knife edge (the gingival margin).

-The free gingiva is about 1-1.5 mm. & separated from the attached gingiva by a free gingival groove both labially and lingually.

1-Free gingiva (Marginal G.)

-This groove appears histologically as a v-shaped notch corresponding to a heavy epithelial rete pegs found between the free and attached gingiva.

-This V-shape due to functional forces upon the free gingiva, folding the movable free part upon the immovable attached gingiva.

rete pegs

free

attached gingiva

Gingival sulcus- Shallow groove lined by non-k. epith.

- Its depth varies from zero-6 mm, and the average 1.8 mm.

-The more shallow the sulcus

no food impaction

More favorable the condition of the gingival Margin. - Lymphocytes and plasma cells are commonly seen in the C.T. of the sulcus as a defense reaction.

مهم

2 -Attached gingiva- Immovable, anchored to the underlying cementum or periosteum.

- Mucogingival junction separates it from alveolar mucosa.

- Its surface shows stippling which is due to functional adaptation to mechanical impacts.

- Absence of the stippling denoting inflammation.

3-Interdental papilla and gingival Col

Gingival col

- Fills the interproximal spaces below the contact areas of the teeth.

-If there is no contact point present, it is reduced. e.g. (diastema).(gap bet. 2 teeth).

- Simulates a tent shape. Its apex tapers to the contact area.

- The Interdental gingival tissue found in the depression between the two peaks of the inter d. pap. is called (Col) and it is non-Keratinized.

NON=KERATINIZED:G.SULCUS….FREE GINIGIVAG. COL….INTERD.PAPILLA

peakpeak

Histology of gingiva

Stratified squamous keratenized epithelium

Lamina propria

Epithelial rete peg

C.T papilla

Tall

Numerous

Slender

Irregular

No submucosa

مهم

1- Orthokeratinized epith ( 15 %): The nuclei and the other organelles are completely absent.

2- Parakeratinized epith ( 75 % ): The nuclei are retained in the whole surface layer and the Keratohyaline granules disappears (SOME ORGANELLS PRESENT).

3- Non Keratinized epith ( 10 % ): The stratum cornium is absent (located at gingival col and gingival sulcus ).

TYPES OF KERATINS:

Gingival fibers

Dento-gingival group

Alveolo-gingival group

Circular group

Dento-periosteal group

Macroanatomy of palate

Incisive papilla

Palatine gingiva

Antro-lateral area (fatty

zone)Postro-lateral

area (glandular

zone)

Rugae area

Median palatine raphe

Soft palate

Uvula

Histology of hard palate

Submucosa

ANTROLATERAL(Fatty zone).

POSTERO LATERAL

)Glandular zone(

Epithelial rete pegs are short , numerous& BOX SHAPED.

Mucosa

FUNCTION:

• 1) ANTROLATERAL (FATTY ZONE):• ACT AS CUSION SO PREVENT BONE RESORBTION.• 2) POSTEROLATERAL(GLANDULAR ZONE):• CUSION • +• PRODUCE MUCOUS SECRETION LUBRICATE FOR

SWALLOW.• (NB) SUBMUCOSA IS ONLY PRESENT IN 1) ANT. LAT.• 2) POST. LAT

DIFFERENTIATE BET.GINGIVA AND HARDPALAT:

1 (SUBMUCOSA

GINGIVA HARDPALAT

2 (RETE PEGS

ABSCENT PRESENT

NUMEROUSTALL

ARREGULARSELENDER

NUMEROUSSHORT

BOX SHAPED

1 -Soft Palate.

2- Lip.

3- Cheek.

4- Inferior (VENTRAL) surface of the tongue

Shor

t and

few

Shor

t and

num

erou

s

Soft Palate:1)ORAL SIDE2)NASAL SIDE

Lip

MUCOUS SIDE

LIP

VERMELION BORDER

LIP

SKIN SIDE

EPITH.epithelium is continuous with that of the hard palate but non-keratinized &HEALTHY LINE INBETWEEN.

NASALSIDELINEDWITH PS. STR.COL.CILIATEDEPITHWITHGOBLTCELLS

THIN& NON -KERATINIZED

THIN&KERATINIZEDstr.squa.epith.

STRATUM LUCIDUIM BET ST. SPINOSUM & ST. CORNIUM.

PRODUCEOILY SUBSTANCE (ELIDINE)

IMP: مهم1)PREVENT WATER EVAPORATION IN HOT WEATHER2)COOLING SKIN

LAMINAPROPRIA

THIN + FEW & SHORT PAPILLAE SEPARATED FROM SUBMUCOSA BY CONTINUOS LAYER OF ELSATIC FIBERS

THINC.T. papillae are numerous and long these deep papillae carry large capillary loops, so the thin layer of epitheliumpermits the red color of blood.(L.CAP LOOP + THIN KERATIN EPITH = RED COLOUR LIPS)

A)ELIDINE :ARISE FROM LIQUIFACTION OF KERATO HYALINE GRANULESB) APENDAGES:1) HAIR FOLLICLE2) SWEAT GL.3) SEBACIOUS GL.

RETE PEGS

FEW&SHORT

SUB -MUCOSA

FAT CELLS &(PURE MUCOUS SAL.GL)

FAT CELLS& LABIAL GL. (PURE MUCOUS)

CHEEK MUCOSAINFERIOR( VENTRAL) SURFACE OF TONGUE

EPITH.THICK& NON KERATINIZED

THIN&NON KERATINIZED

LAMINAPROPRIA

THINTHIN

RETE PEGSSHORT & FEWSHORT & NUMEROUS

SUB –MUCOSA

BUCCAL GL. (MIXED) PREDOMINANTLY MUCOUS

NOT CLEAR (BLEND WITH TONGUE MUSCLES)

Soft palate

Oral side

Nasal side

- Its epithelium is continuous with that of the hard palate but non-keratinized So between them there is a healthy line

Histology of the soft palate

Oral side

Lamina propria is thin with few and short papillae.- A continuous layer of elastic fibers separating lamina propria from submucosa.- The submucosa contains fat cells and mucous glands.

The nasal side is covered with pseudo-stratified columnar ciliated epithelium with goblet cells.

Nasal side

Lip

LipVermilion border

Mucous side

Skin side

Vermilion border

Covered by stratified squamous epithelium with thin layer of keratin.C.T. papillae are numerous and long these deep papillae carry large cappillary loops, so the thin layer of epithelium permits the red color of blood.

Skin

The cells permeated with elaidin (oil) which arise from the liquefaction of keratohyaline granules.

A)Stratum luciduimWITH ELIDIN OIL

B)Skin appendages

Hair follicle

Sebaceous gland

Sweat glands

.

Cheek mucosaN

on

kera

ten

ize

d e

pith

eliu

m Mixed salivary gland

1- Inferior surface of the tongue.- Covered by thin non-keratinized epithelium with short & numerous C.T. papillae.- The submucosa can not be differentiated as a separate layer where it connects the mucous membrane to the C.T. surrounding tongue muscles.

1 -Alveolar mucosa.

2- Vestibular fornix .

3- Floor of the mouth.

Alveolar Mucosa. Vestibular fornix Floor of the mouth

-St. sq. non-k. epith.

-Short few C.T. papillae. - Fiber bundle of L. prop. are thin and regularly interwoven. -Definite submucosa, may contain small mixed S.G. -Numerous elastic fib. (thin) in L. prop., (Thick) in submucosa.

- The same.

-The same.

-Loosely connected to underlying structures to permit the movements of lips, cheeks. - Labial frenums (Median and lateral) are folds of M.M. contain loose C.T. with no muscle f.

-The same.

-The same.

- Adipose T. in the submucosa. -The sublingual and submandibular ducts are present near the covering mucosa in the sublingual folds.

ثاني

Specialized mucosa

Anterior 2/3

Posterior 1/3

Anterior 2/3

Posterior 1/3

Papillary portion

Lymphatic portion(pharyngeal part)

Sulcus terminalis

Tongue papillae

1 -Filliform pap. 2 -Fungiform pap .

4 -Folliate pap.3 -Circumvallate pap.

Taste bud

TASTE BUDSمهم SITE:1)ALL TONGUE PAPILLAE EXCEPT FILLIFORM.

2)SOFT PALAT.

3)POSTERIOR PART EPIGLOTTIS.

A. The Filiform Papillae- Found over the entire dorsal surface. - High narrow, conical structures arranged in rows.- Composed of central C. T. core covered by keratinized epithelium. - The primary papilla (C.T. core) send much smaller 1-2 secondary papillae of C.T. toward the surface. -The epithelium gives projections (threads like) of keratin.- No taste buds.

B. The fungiform papillae

- Project like little mushroom, 0.5-1.5 mm in height.

-Narrow base and smooth rounded tops. Red colour.

- Scattered between filiform

-More numerous at the tip of the tongue than elsewhere.

-Each has a central core of primary C.T. papilla which is covered by thin non-keratinized epithelium.

- Contain taste buds, usually one at the top corner.

- The fungiform papillae which is present at the tip of the tongue are responsible for sweet sensation while those on the lateral borders are responsible for salty sensation.

-Sweet and salty taste are mediated bythe chorda tympani.

-The secondary papillae of lamina propria bring capillaries very close to the surface epithelium which is also relatively translucent, permitting the blood red colour to appear.

Secondary papillae

C. Circumvallate papillaTrough

)FURROW(

- 7-12 in front of the sulcus terminals. - 2.0-3.5 mm in width and height. - Embedded in the tongue and surrounded by deep trough, so that its upper surface are not much higher than the general level of the M. M. of the tongue. - Each has central primary papilla of lamina propria, sending secondary papillae to the st. non-k. epith which covers the whole papilla. - It has a narrow base wide top surface. - Numerous taste buds are present in the lateral aspects of the papilla facing the trough of the papilla. - Von-Ebner serou S.G. open in this cleft at the bottom for cleaning and dissolving the trapped food.- The papilla is responsible for bitter sensation which is mediated by the glossopharyngeal nerve.

- 2 in number present on the lateral border at the boundary of the ant 2/3. - Composed of several leaves(FOLIATE) of varying length arranged vertically. - It is surrounded by furrows in which Von-Ebner Glands open in it. - Numerous taste buds present on the lateral walls.- Covered by St. non-k, epith. -Responsible for sour sensationwhich is also mediated by glossopharyngeal N.

D. Foliate Papilla.

Taste bud

3 -Neuroepithelial cell

1 -Outer supporting cell

2 -Inner supporting cell

Taste pore

Taste sensation

Sweet

Salt

Sour

Bitter

Lingual tonsil (lingual follicle)

Weber salivary gland

The lingual follicle is covered by st. sq. non-kerat. epith. overlying a lymphatic tissue and in many sites extend down into it to from wells or pits called lingual crypts.

Dento-gingival junction

Histogenesis of Dento-gingival junction

1 2

34

Desmolytic enzymes

Epithelial plug

1ry D.G.J (from Reduced E. E.)

2nd D.G.J. (from oral E.)

Histogenesis of Dento-gingival junction

1 2Desmolytic enzymes

Epithelial plug

REDUCED ENAMEL EPITH.S

EC

RE

TE

FUNCTION:

LYSIS OF SURROUNDING C.T

THEN

REE

REE + ORAL EPITH ( + = FUSE WITH )

ORAL EPITH

REE

Histogenesis of Dento-gingival junction

3

4

1ry D.G.J (from Reduced E. E.)

2nd D.G.J. (from oral E.)

THENCENTRAL DEGENERATION OF EPITH PLUG.WITH OUT BLEEDING

1ry D.G.J :REE SECRETE 1RY ENAMEL CUTICLE(ACT AS BASEMENT MEMBRANE LAYER) ATTACHING REE TOTOOTH ENAMEL.

THEN

REE

ORAL EPITH

2nd D.G.J. :REE REPLACED BY ORAL EPITH.ORAL EPITH SECRETE 2RY ENAMEL CUTICLE.[NB]:1)REE IS AN EMBRYONIC TISSUE.2)BASAL LAMINA = BASEMENT MEMB. (ELECT.MICR.) (LIGHT .MICR.)

Histology of Dento-gingival junction

Basal cell layer

External basal lamina

Lamina propria

Superficial flat cells

Hemidesmosomes

Internal basal lamina

(C.T)

Gingival recession ( Passive eruption)

Stages of passive eruption

Anatomical crown

Clinical crown

Coronal end (E)

Apical end C.E.J.

deciduous teeth : 1 year before shedding permanent teeth: Till 20-30 years.

First stage

G.PAPILLA

Second stage

Anatomical crown

Clinical crown

Coronal end (E)

Apical end (C).

Persist till 40 years

Third stage

Anatomical crownClinical crown

Coronal end (C.E.J.)

Apical end (C)

Transitory stage

Fourth stage

Anatomical crownClinical crown

Coronal end (C)

Apical end (C)

Persists till the tooth lost

Stages of passive eruption

Epithelial attachment (mode of attachment).-The attachment of epithelium to the tooth surface is so strong that an attempt to detach the gingiva from the tooth surface the junctional epithelium will tear rather than peel off from the tooth surface.

-This firm union is achieved by what is called epithelial attachment. Under electron microscope this epithelial attachment was found to be basal lamina material to which the hemidesmosomes are attached. It has a thickness of about 400 Å.