Brief histology of oral mucous membrane

1. Oral Mucous Membrane

2. 1.Oral Mucosa The moist lining of the oral cavity is called Oral Mucosa or Oral Mucous Membrane The function of oral mucosa is protection, sensation and secretion It is continuous with the skin outside the oral cavity and differs from it in appearance and structure Dr.Syed Sadatullah King Khalid University

3. Dr.Syed Sadatullah King Khalid University Oral Mucous Membrane

4. Dr.Syed Sadatullah King Khalid University Oral Mucous Membrane Epithelium Lamina Propria Submucosa Periosteum Bone

5. Oral Epithelium Oral epithelium forms the surface of the oral mucosa that forms a barrier between the oral environment and the deeper tissues It is derived from the embryonic ectoderm It is stratified squamous epithelium and may or may not be keratinized Beneath the epithelium lies the connective tissue Dr.Syed Sadatullah King Khalid University

6. Dr.Syed Sadatullah King Khalid University Oral Epithelium -Keratinized

7. Dr.Syed Sadatullah King Khalid University Keratinized oral epithelium Most of the oral mucosal surface is lined by nonkeratinized stratified squamous epithelium except gingiva, hard palate and dorsal surface of the tongue where the epithelium is keratinized The keratinized cells have no nuclei and the cytoplasm is displaced by large numbers of keratin filaments Keratinized epithelium is associated with masticatory function and have four layers of cells

9. 1. Stratum Basale The cells of the stratum basale are cuboidal or low columnar and form a single layer resting on the basal lamina The basal lamina is at the interface of the epithelium and lamina propria Epithelial cells of the oral mucosa are in a constant state of renewal The basal cells show the maximum mitotic activity Dr.Syed Sadatullah King Khalid University

13. Nonkeratinized oral epithelium Nonkeratinized epithelial cells in the superfecial layers do not have keratin filaments in the cytoplasm The surface cells also have nuclei The stratum corneum and stratum granulosum layers are absent This epithelium is associated with lining of the oral cavity Dr.Syed Sadatullah King Khalid University

14. Connective tissue Connective tissue can be differentiated as Lamina Propria and Submucosa Lamina propria Lamina propria is the connective tissue layer immediately below the epithelium It can be divided into papillary layer and the reticular layer Papillary layer forms finger like projections of connective tissue that extend deep in the epithelial layers Dr.Syed Sadatullah King Khalid University

15. Papillary layer is prominent in masticatory mucosa and reticular layer is prominent in lining mucosa Lamina prorpria consists of blood vessels and cells like fibroblasts, cells of blood vessels and lymphatics and nerves Epithelium is avascular, hence its metabolic needs come via the vessels of the lamina propria Dr.Syed Sadatullah King Khalid University

16. Submucosa Submucosa lies below the lamina propria and serves as an attachment between lamina propria and bone or skeletal muscle It is found in the cheeks, lips and parts of the palate It consists of large blood vessels, nerves and lymphatics and its functions are nutrition and defense Dr.Syed Sadatullah King Khalid University

17. 2. Functional types of Oral Mucosa Lining mucosa and Masticatory mucosa Lining mucosa Lining mucosa covers all soft tissue of the oral cavity except the gingiva, hard palate and the dorsal surface of the tongue Lip Lip is covered by lining mucosa Dr.Syed Sadatullah King Khalid University Lip with skin on outer surface and lining mucosa on inner surface

18. Vermilion border The junction between the skin and mucous membrane is known as the vermilion border Here the epithelium is thin therefore, the red blood cells in the capillaries show through contributing to the vermilion colour Dr.Syed Sadatullah King Khalid University Vermelion Zone

19. Ventral surface of the tongue The lining mucosa here contains both lamina propria and submucosa The submucosa merges with the muscle bundles of the ventral surface of the tongue Dr.Syed Sadatullah King Khalid University Ventral surface of tongue

20. Cheek In the cheek the underlying submucosa contains fat cells and small mixed salivary glands Dr.Syed Sadatullah King Khalid University Cheek

21. Floor of the mouth The mucous membrane of the floor of the mouth is thin and loosely attached to the underlying structures Dr.Syed Sadatullah King Khalid University Floor of the mouth

22. Masticatory mucosa Masticatory mucosa covers the gingiva and hard palate In edentulous mouth, masticatory mucosa covers the chewing surface of the dental arches Gingiva Gingiva has keratinized or parakeratinzed epithelium with no submucosal layer It develops from the union of oral epithelium and reduced enamel epithelium of the developing tooth Gingiva can be classified as free gingiva, attached gingiva and interdental papilla Dr.Syed Sadatullah King Khalid University

23. Dr.Syed Sadatullah King Khalid University Normal Gingiva

24. Dr.Syed Sadatullah King Khalid University Development of gingiva from oral epithelium and reduced enamel epithelium

25. Dr.Syed Sadatullah King Khalid University Anatomy of gingiva

26. Free gingiva (or marginal gingiva) It is that part of the oral mucosa that surrounds the necks of the teeth and forms the free margin of the gingival tissue It is differentiated apically from the attached gingival by the free gingival groove The inner side of it forms the gingival sulcus The free gingival mucosa is composed of stratified squamous epithelium that may be keratinized, parakeratinzed or sometimes nonkeratinized Dr.Syed Sadatullah King Khalid University

27. Dr.Syed Sadatullah King Khalid University Free gingiva

28. Dr.Syed Sadatullah King Khalid University Alveolar Mucosa (Arrows - Interdental Papillae)

29. Attached gingiva The attached gingiva lies between the free gingival groove and the alveolar mucosa The junction of the attached gingiva and the alveolar mucosa is called mucogingival junction In healthy mouth attached gingiva shows stippling (orange-peel appearance) which is a characteristic of this type of mucosa Dr.Syed Sadatullah King Khalid University

30. Dr.Syed Sadatullah King Khalid University Histology of gingiva

31. Dr.Syed Sadatullah King Khalid University Mucogingival junction (arrows)

32. Dr.Syed Sadatullah King Khalid University Alveolar Mucosa

33. Interdental papilla Interdental papillae are those parts of gingival tissue that appear in-between teeth apical to the contact points Interdental grooves extend vertically between the interdental papilla corresponding to the depressions between the roots Confirming to the shape of the interproximal contact area is a valley like depression in the interdental papilla called Col . This depression lies in the facial and lingual plane Dr.Syed Sadatullah King Khalid University

34. Dr.Syed Sadatullah King Khalid University Interdental Papilla (arrow)

35. Dr.Syed Sadatullah King Khalid University Diagram of positional relation of col in health and disease for canine, premolar and molar Col accentuated during inflammation (arrows)

36. Junctional epithelium Junctional epithelium forms the seal of the gingival epithelium and the tooth It forms the floor of the gingival sulcus and extends apically to the enamel of the tooth Disturbances of epithelial attachment results in deepening of the sulcus which is a sign of gingival/periodontal disease Dr.Syed Sadatullah King Khalid University

37. Dr.Syed Sadatullah King Khalid University Histology of gingiva

38. Hard palate The surface of the hard palate that is visible in the mouth is covered by masticatory mucosa The lateral regions of the posterior part contains palatine glands These glands are purely mucous glands The midline of the hard palate is called median raphe where there is no submucosa A series of folds appear in the anterior part of the palate called rugae Dr.Syed Sadatullah King Khalid University

39. Dr.Syed Sadatullah King Khalid University Hard Palate and Soft Palate

40. Dr.Syed Sadatullah King Khalid University Palatal rugae (arrow)

41. 3 Mucosa of the Tongue Specialized mucosa covers the dorsal surface of the body of the tongue The connective tissue binds the epithelium to the underlying skeletal muscle The epithelium is modified, keratinized, stratified covered with papillae, which can be seen by naked eye Dr.Syed Sadatullah King Khalid University

43. Dr.Syed Sadatullah King Khalid University Cross section of tongue

44. 1. Filliform papillae Filliform papillae are pointed extensions of the keratinized epithelial cells They are the most numerous papillae of the tongue They are not associated with taste buds Dr.Syed Sadatullah King Khalid University Scanning electron micrograph of Filliform papillae (arrow)

45. Dr.Syed Sadatullah King Khalid University Filliform Papillae

46. 2. Fungiform papillae Fungiform papillae are fewer than the filliform papillae and are scattered over the dorsal surface of the tongue They are rounded elevations above the surface of the tongue They have taste buds on their superior surfaces The surface of fungiform papillae is not keratinized Dr.Syed Sadatullah King Khalid University

47. Dr.Syed Sadatullah King Khalid University Scanning electron micrograph of Fungiform papillae (arrow) surrounded by Filliform papillae

48. Dr.Syed Sadatullah King Khalid University Fungiform Papillae

49. 3. Circumvallate papillae The circumvallate papillae are located at the junction of the anterior two thirds (body) and posterior one thirds (base) of the tongue There are eight to twelve in number and are bigger than fungiform papillae Circumvallate papillae are lined with taste buds and also openings of serous glands The secretion from the serous glands washes away food for renewal of taste Dr.Syed Sadatullah King Khalid University

50. Dr.Syed Sadatullah King Khalid University Circumvallate Papilla and Taste buds (arrows)

51. 4. Foliate papillae Foliate papillae are located in the furrows along the posterior sides of the tongue They may be lined with taste buds They are not prominent in human beings Dr.Syed Sadatullah King Khalid University