Dr: Mahmoud 3mmar

Mobile: 0106 39 700 30

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m.3mmar9428@yahoo.com

Oral mucosa( lecture 1 )

Contents of chapter:- 1) definition. 2) functions. (protection , sensation , secretion). 3) organization. (outer vestibule & oral cavity proper). 4) classification. (masticatory & lining & specialized). 5) histological str. (oral epith.,lamina propria , basement memb)

Oral mucosa: (epith + C.T) its structurally , functionally transitional zone between the skin & GIT , exhibits features of both.

its like GIT in : its bathed in fluid & have high rate of turnover. like skin in : its possesses a stratified epith. Which

is keratinized in many places thus prevents , limits diffusion across both direction.

skin Oral mucosanot moist moisture

sebacious salivary glands

found not Hair follicle

more less firmness

less more Surface smoothness

less deeply colored color

Human tissues

1 )epithelial

3 )mascular

4 )nervous

2 )connective

General features of epithelial tissue:

1) cells rests on basement membrane. & have free surface

2) cells adhere to each other in one layer or more. 3) cells a-vascular but have nerve fibers. 4) cells cover a surface , lined cavity and form glands. 5) basal surface contact the basement membrane while free surface interface with external environment or space within the body.

Oral mucosa has 2 main tissue component: 1) stratified squamous epith. (oral epith.). 2) underlying C.T layer (lamina propria).

rete-pegs: part of oral epith. Which interdigitate with C.T papillae.

connective tissue papillae: irregular upward projection of C.T which inter face with rete-pegs.

Functions of the oral epithelial:-(protection , sensation , secretion ). 1) protection: a- separates ,protect deeper tissues & organs in oral region from the environment of oral cavity. b- its show number of adaptation of epith , C.T to withstand force of mastication & it acts as barrier to microorganism , toxins.

2) sensation: its provide information about events in oral cavity where as lips , tongue perceive stimuli outside the mouth.

a) in the mouth receptors respond to temperature , touch , pain , taste and thirst . b) tongue has taste buds. c) reflexes (swalloing , salivation , gagging) are initiated by receptors in the oral cavity.

3) secretion: major secretion associated with oral mucosa is saliva from major , minor salivary glands which maintains a moist , lubricant surface of the oral mucosa . ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ

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3-organization: 1) outer vestibule bounded by lips , checks.

2) oral cavity proper : superior zone of oral cavity proper formed by hard & soft palate. inferior border formed by floor of mouth , tongue.

4-classification of oral mucosa: (25%masticatory mucosa & 60%lining mucosa & 15%specialized mucosa).

1) masticatory mucosa: (25%) this parts from oral mucosa subjected to force of mastication & pressure this parts are : 1-Gingiva 2-Hard palate. *) this parts are rubbery , resistant & keratinized or para-keratinized stratified squamous epith.

2)Lining mucosa (60%): its presen in areas which not subjected to high force but its must be mobile , distensible .

1.2.3- Its buccal , labial , alveolar mucosa 4.5- floor of mouth & ventral tongue 6- Soft palate.

Its non keratinized stratified squamouth epith.

specialized mucosa (15%):its mucosa covering the dorsal surface of the tongue and contains different types of taste buds , papillae and lingual tonsils , lymph tissues.

5) Histological structure:

Basal cell layer

Prickle cell layer

Granular cell layer

Cornified cell layer

basal

intermediate

superficial

3-Lamina propria

Stratified squamous epithelium

KeratinizedNon-

keratinized:

•ortho-keratin.•para-keratin.

Papillarylayer

Reticular layer

glands or

fat cells

May or

may not be

present

1-Oral epithelium

4-

Submucosa

Basement

membrane

2-basement membrane

Histological structure: (oral epith. & lamina propria & basement membrane in between &

sub-mucosa )ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ

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1) Oral epithelial: its ectodermal in origin formed of stratified squamous epith which is keratinized in some areas & Non-kerarinized in others.

N.B: stratum = layer

Non-keratinized epith. Keratinized epith.

Stratum basale Stratum basale (basal layer)

Stratum spinosum Stratum spinosum (prickle)(prickle layer)

Intermediate layer Stratum granulosum(granular layer)

Superfacial layer Stratum corneum (keratinized layer)

Keratinized Epithelium Nonkeratinized Epithelium

Oral epitheliu

m

1) Keratinized epithelium: this type found in areas which subjected to force like gingiva , hard palate (masticatory mucosa).

N.B: cells which form this layer called keratocytes or keratinocytes.

*Cells are arranged in 4 layers (basal & spinous & granular & cornified). the names of layers derived from their morphology.

Layers of keratinized epith (basal&prickle&granular&cornified).ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ

ــــــــــــــــــــــــــــــــــــ1)Basal layer: 1. its single row of columnar or cuboidal cells that is closely attached to

each other & arranged on basement membrane.

2. Cells posses all usual organelles & tonofilaments (tonofilaments: its fibrous protein synthesis by ribosomes , seen as long filaments chemically its cytokeratin ).

3. Its site of cell division since its divided into 2 cells (progenitor cells , mturative cells)

*progenitor cells: remain in base to divide again. *maturative cells : migrate toward the surface.

2) Spinous cell layer: 1. Its consist of several rows of polyhedral cells of different shapes , size.2. Spinous layer & basal layer constitute more than half thickness of the epith.3. Cells joinded together by intercellular bridges giving the cells prickly apperance.4. Wide inter cellular space compared with Non-keratinized epith.5. Its most active cells in protein synthesis.6. Numerous , well developed organelles.7. No sudden changes in appearance of cells & there is gradual

decrease in synthetic activity through the layer.8. In the upper part of this layer there are odland’s bodies .

odland’s bodies: (keratinosomes or membrane coating granules).• Its present in superfacial layer of prickle layer or in first layer of granular layer• Its may originate from golgi complex.• This granules discharged in intercellular space, act as barrier to penetration of

forgein substance.• Its responsible for thickning of cell membrane.

3.Granular cell layer: 1. Its several rows of flattened epith. Cells.2. Many organelles are reduced , cytoplasm will be occupied

by tonofilaments & tonofibrilis.3. Cells contains large number of small granules called

(keratohyaline granules).4. Odlands body discharge into inter-cellular space which act

as barrier & increase the thickness of epith.

4.Cornified layer: 1. Its present in keratinized epith as final stage of

maturation.2. Cell loss all organelles & filled by closely packed

tonofilaments which are surrounded by matrix protein

and this structure called keratin.3. Its shed (process of desquamation).4. Weak desmosomes to allaow desquamation.5. Its provide mechanical , chemical protective function to

the mucosa.

2. Non-keratinized epith.: (in this type there absence of cornified & granular cell layer).

1. Epith. Is thicker , outer half of epith. Shows changes which distinguished them from basal , prickle cells.

2. Outer half divided into 2 zones (intermediate , superfacial layer).

3. This cells increase in size and there is accumulation of glycogen , presence of keratohyaline granules which appear more regular & not associated by tonofilaments.

4. cells of Outer 2 strata are tightly packed together thus intercellular space nearly absent.

5. Cells of stratum intermedium contains odlands body with there size , shape , location differ from those found in keratinized epith.

6. Super facial layer contains nucleus , few organelles.

Thanks

Dr:3mmar