Oral mucosa

Dr suhad almaani

1. Oral mucosa

2. definition Mucous Membrane : Moist lining of the gastrointestinal tract, nasal passages and other body cavities that communicates with the exterior of the body . ( In the oral cavity the lining is called as oral mucous membrane or oral mucosa ) Function : MAINLY: protection( physical barrier,immunological defence ) Secretion : minor glands, lubrication . Sensation: Temperature (heat and cold), touch, pain, taste . Proprioception

3. Basic structure Skin : Epidermis + Dermis . Oral Mucosa : 1- Epithelium (keratinized /non keratinized stratified squamous epithelium ). 2- C.T ( lamina propria ) . 3- Submucosa ( not always present )

4. How is the oral mucosa different from skin? Color :more deeply coloured . 2- Moist surface 3. Absence of hair follicles . 4- Presence of minor salivary glands in oral mucosa . Texture of surface: Oral mucosa is smoother than the skin 6 .Firmness: Oral mucosa varies in its firmness.

5. Oral mucosa classifications Lining Mucosa: 60% of total mucosa. Covers the floor of mouth,ventral (underside)tongue, alveolar mucosa, cheeks, lips and soft palate. Does not function in mastication and therefore has minimal attrition. Non-keratinized stratified squamous epithelium. soft, moist, ability to stretch and compress .

6. Masticatory Mucosa: 25% of total mucosa. Primary mucosa to be in contact with food Gingiva (free, attached and interdental ) and hard palate. Keratinized stratified squamous epithelium rubbery, resilient. Specialized : Dorsum of tongue ( anterior 2/3 )surface associated with the lingual papillae Vermilion zone of the lips

7. Histology of oral mucosa There are mainly 2 components : Oral epithelium ( stratified squamous ) C.T ( L. propria ) / submucosa (loose C.T contains vessels,nerves ,muscles) . Distinct B.M between epith ./C.T Indistinct between L.p / submucosa .

8. layers of oral epithelium .…… Keratinized Stratum basale ( germinativum ) Startum spinosum (prickle ) Stratum granulosum Stratum corneum Non-keratinized Stratum basale Startum spinosum Stratum Intermedium Stratum Superficiale

9. Stratum BASALE Single cuboidal cell layer Adjacent to lamina propria The only layer where mitosis occurs Are all stem cells? Least differentiated cells Non-keratinocytes cell present

10. Stratum Spinosum Several cells thick Round or Ovoid cells Larger and more mature than those of startum basale Contain - Tonofilaments & involucrin - Phospholipid granules ( Odland bodies) in the upper part of spinosum -Increased desmosomes (shrinkage during preparation gives the spiny appearance)

11. Stratum Granulosum Cells of further increase in maturation Cells larger and flatter Contain - Tonofilaments & tonofibrils that occupy the cytoplasm - Keratohyline granules (contain profilaggrin )

12. Stratum corneum In keratinized epithelium - Highly mature epithelial cells ( squames ) -All cellular organelles and nucleus lost ( orthokeratinization ) - In gingiva, nuclei may be retained ( para keratinization ) - cells are packed with Keratin Keratin consist of - Tonofilaments surrounded by Filaggrin (matrix protein) Desmosomes are weak to allow for shedding (desquamation) Involulcrin is cross-linked to form a cornified envelop beneath plasma membrane

13. Stratum corneum In non-keratinized epithelium - No Keratin - Tonofilaments are less and under-developed - lack keratohyline granules - this layer is less distinct - the outer layers of non-keratinized epithelium may be termed stratum superficiale - The layers below may be termed startum intermedium

14. Keratinized Vs non- kertainized keratinized Cells have keratohyline granules (contain profilaggrin essential to stabilize keratin filaments). Cells of superficial layers 1- loss of nuclei completely ( orthokeratinized )or partially ( para keratinized) 2-No organelles at all Non -keratinized Cells lack keratohyaline granules. Cells of superficial layers have nuclei, organelles. Only Involuricin protein is produced No filaggrin or loricin so tonofilaments are less developed and dispersede

15. cytokeratins CK : intermediate filaments that show high specificity for epithelial cells .at least 22main CK polypeptides are known. Function : component of cell cytoskeleton. component of desmosmes and hemidesmosomes .( E.bullosa mutant CK14 ) 2 CK types : Basic, high Mwt CK type 2 ( numbers 1-8) Acidic,low Mwt type 1 ( numbers 9-22) Each epith.cell express at least one pair (component of type 1 + component of type 2

16. DistRibution of ck in epithelium Masticatory mucosa CK (1,10) (2,11) Lining mucosa (4,13) Basal cell keratinocytes for all SSE (5,14) Hyperproliferative epith .(6,16) Basal cell Ca.(17) Odontogenic epith . CK 19 Ventral of tongue (5,6,14 ) Soft palate (7,8,18) high level of 19 Alteration of CK profile indicates dysplastic changes or pathologic changes e.g masticatory mucosa shows production of CK 4 indicates gingival inflamation .

17. Types of cells in epithelium Keratinocytes 90% Cells have tonofilaments Cytokeratin (type of intermediate filaments) desmosomes Non- keratinocytes Not related to epithelial maturation Cells lack tonofilaments ( called Clear cells ) halo around nuclei when stained for CK. No desmosomes EXCEPT MERCKLE CELLS

18. Non- keratinocytes Melanocytes : Produce the pigment melanin using the enzyme tyrosinasedendritic (long process that extend through upper layer), packed with granules ( melanosomes ), located in stratum germinativum , derived from neural crest cell Langerhans : Dendritic, contain birbeck granules, located in the layer above stratum germinativum , derived from bone marrow precursors, antigen-presenting cells, involved in contact- hypersensetivity reaction, antitumour immunity and graft rejection. Merckle cells : Not dendritic, located in stratum germinativum of masticatory epithelium, absent in lining epithelium, closed apposed to nerve fibers, thought to act as a receptor, derived from neural crest cell, posess keratin filaments and desmosomes, small membrane bounded vesicle may liberate neurotransmitter.

19. Lamina propria Superficial papillary layer (associated with epthelial rete ridges) Collagen fibers are thin and loosely arranged. deeper reticular layer : netlike arrangement of dense 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 parellel to surface Lamina propria also contains various cells, blood vessels, nerves and fibers (collagen and elastic) embedded in an amorphous ground substance

20. Structure of L.P : FIBRES : Collagen fibers (80% type 1, 18 % type 3 ) run in bundles Elastin fibers ( for flexibility ) run singly not in bundles . Oxytalan . GROUND SUBSTANCE : Hydrated gel og proteoglycans and glycoproteins CELLS : main cells FIBROBLASTS ( turn over of fibers and synthesis of ground substance )

21. Basement membrane Network of type 4 collagen ( non- fibrillar ) Proteoglycans , glycoproteins Synthesized by epithelial cells. Hemidesmosomal attachment.( MMP autoantibodies agst transmembrane molecules bullous pemphigoids antigen BP180,230 ) Under E.M lamina lucida (directly under epith ) , lamina densa

22. Masticatory vs lining mucosa Surfaces exposed to shear compressive forces during mastication epithelium :Thick keratinized lamina P. :Thick dense Numerous elongated Rete pegs. No submucosa Hard palate.gingiva epith : Non-keratinized Epithelial junction with C.T (papillae) smoother,short /flexibility L.P is thinner with fewer collagen ,more irregular course,more elastin Thick submucosa

23. Histology of Hard Palate Thick orthokeratinized (or parakeratinized in areas) epithelium showing ridges ( rugae ) Lamina propria shows long papillae with thick dense connective tissue In central area NO submucosa is present But where it joins alveolus submucosa is present since it contains neurovascular bundle, also fattu zone anteriorly , glandular zone ( minor salivary glands) posteriorly

24. Soft palate A: Hard Palate B; Soft palate C: Nasal cavity Nonkeratinized Highly vascularized so more pink than hard palate 2. Lamina propria and submucosa present (unlike hard palate when only lamina propria is noted – mucoperiosteum ) Submucosa contains salivary glands and muscle soft palate

25. Similar to lips and soft palate Nonkeratinized stratified squamous epithelium, lamina propria and submucosa Submucosa of cheeks contain fat cells along with lobules of minor salivary glands and muscle fibers Cheeks ( Buccal Mucosa)

26. Ventral surface of tongue Floor of mouth Nonkeratinized stratified squamous epithelium, lamina propria and submucosa Extremely dense muscle fibers interlacing connective tissue fibers in submucosa Nonkeratinized stratified squamous epithelium, lamina propria and submucosa Epithelium is loosely attached to lamina propria No muscle

27. Specialized mucosa Anterior 2/3 of the tongue ( masticatory but with taste buds ) Filiform papillae (hair like ) dorsum of tonge,keratinized Fungiform ( mushroom like) non- keratinized,at tongue tip Foliate ( leaflike ) post.lat.margin of tongue. Non-keratinized Cicumvallate : non keratinized,taste buds present in epithelium of trench surrounding it.

28. Filiform papilla: Makes up majority of the papillae and covers the anterior part of the tongue. They appear as slender, threadlike keratinized projections (~ 2 to 3 mm) of the surface epithelial cells. These papillae facilitate mastication (by compressing and breaking food when tongue is apposed to the hard palate) and movement of the food on the surface of the tongue. The papillae is directed towards the throat and assist in movement of food towards that direction. NO TASTE BUDS.

29. Fungiform papilla : (Fungus-like) These are interspersed between the filiform papilla. More numerous near the tip of the tongue. Smooth, round structures that appear red because of their highly vascular connective tissue core, seen through a thin, nonkeratinized stratified squamous epithelium. Taste buds are usually seen within the epithelium.

30. Foliate Papilla : (Leaf-like). Present on the lateral margins of the posterior tongue. Consist of 4 to 11 parallel ridges that alternate with deep grooves in the mucosa, and a few taste buds are present in the epithelium. They contain serous glands underlying the taste buds which cleanse the grooves.

31. Circumvallate papilla : (Walled papilla). 10 to 14 in number these are seen along the V-shaped sulcus between the base and the body of the tongue. Large, ~ 3 mm in diameter with a deep surrounding groove. Ducts of von Ebner glands (serous salivary glands) open into the grooves. Taste buds are seen lining the walls of the papillae.

32. Microscopically visible barrel-shaped bodies found in the oral epithelium. Usually associated with papillae of the tongue ( circumvallate , foliate and fungiform ). Also seen in soft palate, epiglottis, larynx, and pharynx. Referred to as NEUROEPITHELIAL STRUCTURES. But most correctly referred as epithelial cells closely associated with clib -shaped sensory nerve endings. These nerves arise from the chorda tympani in anterior tongue and glossopharyngeal in posterior tongue and come to lie among the taste cells. Each taste bud has ~ 10 to 14 cells. Majority are taste cells with elongated microvilli that project into the taste pore. (Epiglottis and larynx – Vagus nerve Taste Buds : Unique sense organs that contain the chemical sense for taste

33. Taste Buds in the Human Adult Location Number Tongue 10,000 Soft palate 2,500 Epiglottis 900 Larynx/pharynx 600 Oropharynx 250 4 taste sensations: Sweet, salty, sour and bitter Sweet and salt: ant tongue Sour: lateral tongue Bitter: region of circumvallate papilla

34. 2-vermilion border ( mcj ) Junction between skin and labial mucosa. Red zone ( epith.is thin and translucent,C.T contains capillary loop) Thin keratinized epith . Papillae are long and narrow no sweat glands Few sebacous glands`

35. A: Skin B: Vermillion zone C: Oral (labial) mucosa D: Minor salivary glands

36. junction of the mucous membrane of the oral cavity with the skin of the lip ( A ). Skin is to the right ( B ) and is composed of the epidermis (epithelial layer) and the dermis (dense connective tissue layer). Mucosa ( C ) on the left, is composed of epithelium and lamina propria (dense connective tissue layer). mucocutaneous junction ( A ) - the epithelium of the mucosa is continuous with that of the skin and the lamina propria is continuous with the dermis. .

37. Turnover time : Estimated time necessary to replace all the cells in the epithelium: Skin: 52 to 75 days Gut: 4 to 14 days Gingiva : 41 to 57 days Cheek: 25 day Junctional epithelium of gingiva : 5-6 days Nonkeratinized epithelium e.g buccal mucosa turns over faster than keratininzed epithelium hard palate Clinical correlation: Oral ulcers during cancer chemotherapeutic treatment ( growth factors )

38. gingiva

39. The gingiva is the part of the oral mucosa that covers the alveolar processes of the jaws and surrounds the necks of the teeth.75% parakeratinized,10% non- keratinized , orthokeratinized . • The gingiva is divided anatomically into: 1. Marginal 2. Attached 3. and Interdental areas

40. Gingival cuff (DGJ) Sulcular epith + junctional epithelium. Sulcular epith.:non-keratinazed SS. If exposed turned into keratinized SS. Junctional epithelium is non keratinized SS BUT IT IS ODONTOGENIC from Reduced Enamel Epith . Rather than being from oral mucosa ( cytokeratin profile CK 19) Highest rate of turn-over ( 5-6days) Has 2 basal laminae (internal with enamel ,external with L.p ) Hemidesmosomes present Protective role (wide intercellular spaces for passage of crevicular fluids)

41. Gingival fibers 1- Dentogingival : from Cementum above alveolar crest to gingiva 2- longitudunal : extends within free gingiva along whole arch. 3- circular : encircle tooth with interdental gingiva and marginal gingiva .some attach to cementum , bone,adjacent tooth. 4- Alveogingival : crest of alveolar bone , interseptal bone coron al to gingiva . 5-Dentoperiosteal : only in labial & ling.gingiva from cementum to Periosteum (pass over alv.crest ) 6-Transseptal : horizontally from root of one tooth to the root of adjacent one. 7-Semicircular : from cementum of one side of tooth to the opposite side of same tooth. 8- Transgingival : from cervical cementum to marginal G of adjacent tooth 9- Interdental : connect buccal & ling. Interdental papillae 10-Vertical : attached gingiva coro nally to MG or ID gingva .

42. THANK YOU ……