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Oral Mucosa

Oral Mucosa Report

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Oral Mucosa

  1. 1. ORAL MUCOSA The oral cavity is lined with an uninterrupted mucous membrane, which is continuous with the skin near the vermilion border of the lips and with the pharyngeal mucosa in the region of the soft palate and anterior pillars of fauces. The epithelium of the oral mucosa originates partly from the ECTODERM (lips, vestibule, gingiva, cheeks, palate, floor of the mouth), and pertly from the endoderm (tongue).
  2. 2. MASTICATORY MUCOSA • free and attached gingiva and hard palate comes in primary contact with food during mastication and is keratinized. LINING MUCOSA • the lips cheeks, vestibule, floor of the mouth, interior surface of the tongue and soft palate. It does not function in mastication and therefore has little attrition. It is soft, pliable and non-keratinized. SPECIALIZED MUCOSA • on the dorsal surface (dorsum) of the tongue. It is covered with cornified epithelial papillae
  3. 3. Protection • acts as major barrier to microorganisms Sensation • receptors that respond to temperature, touch, pain, taste; initiates reflexes such as swallowing, gagging and salivation Secretion • saliva, contributes to the maintenance of moist surface Permeability and Absorption • thinnest epithelial regions, floor of the mouth, more permeable than other areas Thermal Regulation • dogs, body heat is dissipated thru the oral mucosa by panting
  4. 4. Two main tissue components: • stratified squamous epithelium Oral epithelium • undderlying connective tissue layer Lamina Propia or Corium The oral mucosa is attached to the underlying structures by a layer of loose fatty or granular connective tissue containing major blood vessels and nerves
  5. 5. • structureless layer about 1 – 2 micrometers thick; interface between epithelium and connective tissue Basement Membrane • irregular and upward projections of connective tissue Connective tissue papilla • or rete pegs, epithelial ridges or pegs that interdigitate with the connective tissue papilla Rete Ridges
  6. 6. Orthokeratinization Keratinization (types) • About 20-30% of the gingiva, the stratum corneumis homogenous and made up of flat, closely packed keratinized cells without nuclei Parakeratinization • Approximately 50-70% of the cases, the stratum corneum is homogeneous and consists of flat keratinized cells with pyknotic nuclei and remnants of cytoplasmic organelles Incomplete Keratinization • - Least common type, approximately 7-10% of cases and is seen only in the region of the marginal gingiva. Stratum corneum is homogenous and consists of 2 cell types, which occasionally form 2 superimposed layers: the first type of cell is the same as cornified cell of a parakeratinized stratum corneum; the 2nd type is different from keratinized cells and seems to reach the stratum corneumand its surface without being transformed nto a keratinized cell.
  7. 7. 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
  8. 8. 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. 9. Layers of the Keratinized Surface Epithelium 1.Stratum Basale 2.Stratum Spinosum 3.Stratum Granulosum 4.Stratum Corneum
  10. 10. 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
  11. 11. STRATUM SPINOSUM Stratum spinosumis usually several cells thick They are shaped like polyhedron with short cytoplasmic processes The stratum basale and the first layers of stratum spinosumare referred to as stratum germinativum because these cells give rise to new epithelial cells
  12. 12. STRATUM GRANULOSUM Cells of stratum granulosumare flat and are found in layers of three to five cells thick This layer is prominent in keratinized epithelium (and absent in nonkeratinized epithelium) These cells have keratohyaline granules in their cytoplasm Keratohyaline granules help to form the matrix of the keratin fibres found in the superficial layer
  13. 13. STRATUM CORNEUM Cells of stratum corneum are flat, devoid of nuclei and full of keratin filament surrounded by a matrix These cells are continuously being sloughed and are replaced by epithelial cells that migrate from the underlying layers
  14. 14. 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 granulosumlayers are absent This epithelium is associated with lining of the oral cavity
  15. 15. 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 Lamina propia can be divided into: 1)papillary layer - prominent in masticatory mucosa 2)reticular layer-prominent in lining mucosa • Lamina propria 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
  16. 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 of mucosa are nutrition and defensive.
  17. 17. Functional types of Oral Mucosa • Lining mucosa covers all soft tissues of the oral cavity except the gingiva, hard palate and the dorsal surface of the tongue A) Lining mucosa Lip Lip is covered by lining mucosa Lip with skin on outer surface and lining mucosa on inner surface
  18. 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
  19. 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
  20. 20. Cheek In the cheek the underlying submucosa contains fat cells and small mixed salivary glands
  21. 21. Floor of the mouth The mucous membrane of the floor of the mouth is thin and loosely attached to the underlying structures
  22. 22. • Masticatory mucosa covers the gingiva and hard palate. • In edentulous mouth, masticatory mucosa covers the chewing surface of the dental arches. B) Masticatory mucosa 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
  23. 23. 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
  24. 24. 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
  25. 25. The different papillae found on the dorsal surface of the tongue are: 1.Filliform papillae 2.Funginform papillae 3.Circumvallate papillae 4.Foliate papillae
  26. 26. 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 Scanning electron micrograph of Filliform papillae (arrow)
  27. 27. 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
  28. 28. 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
  29. 29. 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