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ORAL CAVITY-2

ORAL CAVITY-2. This resource is licensed under the Creative Commons Attribution Non-Commercial & No Derivative Works License. Objectives. Recognise and describe a section through an enamel organ, identifying the main features and constituent tissues.

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ORAL CAVITY-2

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  1. ORAL CAVITY-2 This resource is licensed under the Creative Commons Attribution Non-Commercial & No Derivative Works License

  2. Objectives Recognise and describe a section through an enamel organ, identifying the main features and constituent tissues. Recognise and describe a section of the developing oral cavity (low power), distinguishing between the main structures and their organisation. Recognise and describe different cellular and extracellular components of the developing tooth (low power) appreciating their arrangement and any changes which occur during eruption. Distinguish and describe the characteristic main features of serous, mucous and mixed salivary glands (high power).

  3. Identify at low magnification : • Oral cavity. • Tongue. • Eyes. • Developing nasal cavity. • Mandible. • Other bones of skull. • Developing enamel organs. • Developing brain. SLIDE 10/11 Head 1.0 mm

  4. Identify at low magnification : • Oral cavity. • Tongue. • Eyes. • Developing nasal cavity. • Mandible. • Other bones of skull. • Developing enamel organs. • Developing brain. SLIDE 10/11 Head 8 6 6 4 3 3 1 7 7 2 5 5 1.0 mm

  5. SLIDE 10/11 Head At a higher magnification identify developing teeth and developing mandible. 250 µm

  6. SLIDE 10/11 Head T : developing teeth B : bone of mandible T At a higher magnification identify developing teeth and developing mandible. oral cavity T B tongue 250 µm

  7. SLIDE 10/11 Head Identify : 1. Position of dental lamina. 2. Inner and outer epithelium. 3. Stellate reticulum. 4. Dental papilla. 100 µm

  8. SLIDE 10/11 Head oral cavity dental lamina Identify : 1. Position of dental lamina. 2. Inner and outer epithelium. 3. Stellate reticulum. 4. Dental papilla. S outer epithelium D inner epithelium mandible S : stellate reticulum D : dental papilla 100 µm

  9. SLIDE 10/11 Head What are the main constituent tissues of an enamel organ? 50 µm

  10. What are the main constituent tissues of an enamel organ? Outer epithelium. Stellate reticulum. Inner epithelium which becomes the enamel secreting ameloblast layer. SLIDE 10/11 Head dental lamina outer epithelium What are the main constituent tissues of an enamel organ? S : stellate reticulum S inner epithelium cells elongate becoming ameloblasts dental papilla 50 µm

  11. SLIDE 10/11 Head dental lamina outer epithelium What type of tissue is stellate reticulum? S : stellate reticulum S inner epithelium cells elongate becoming ameloblasts dental papilla 50 µm

  12. What type of tissue is stellate reticulum? Stellate reticulum consists of star shaped cells lying between the outer and inner epithelial layers; it has the appearance of connective tissue but is of epithelial derivation. SLIDE 10/11 Head dental lamina outer epithelium S : stellate reticulum S inner epithelium cells elongate becoming ameloblasts dental papilla 50 µm

  13. SLIDE 10/11 Head 1.0 mm In the lower jaw identify Meckel’s cartilage. 250 µm

  14. SLIDE 10/11 Head oral cavity tongue E 1.0 mm In the lower jaw identify Meckel’s cartilage. E : enamel organ Meckel’s cartilage developing mandible 250 µm

  15. SLIDE 10/11 Head What is the origin and function of Meckel’s cartilage? 100 µm

  16. What is the origin and function of Meckel’s cartilage? The lower jaw is formed in the embryo of cartilage. This cartilage does not undergo ossification, but acts as a model for the deposition of bone from surrounding connective tissue. This cartilage (Meckel’s cartilage) is later resorbed. SLIDE 10/11 Head What is the origin and function of Meckel’s cartilage? Meckel’s cartilage developing mandibular bone 100 µm

  17. SLIDE 10/11 Head What is the most prominent feature of the mandibular bone closest to the developing enamel organ? 100 µm 25 µm

  18. What is the most prominent feature of the mandibular bone closest to the developing enamel organ? The presence of osteoclasts (giant multinucleated cells derived from monocytes) involved in the resorption of matrix in bone re-modelling. SLIDE 10/11 Head B : mandibular bone B What is the most prominent feature of the mandibular bone closest to the developing enamel organ? osteoclasts B 25 µm

  19. SLIDE 12 Developing molars At low magnification identify the position of the molar teeth and the labio-gingival groove within the oral cavity. 1.0 mm

  20. SLIDE 12 Developing molars L : labio-gingival groove M : molars At low magnification identify the position of the molar teeth and the labio-gingival groove within the oral cavity. M M oral cavity L L tongue M M 1.0 mm

  21. SLIDE 12 Developing molars Select a developing tooth sectioned to show most areas from crown to root. 1.0 mm 0.5 mm

  22. SLIDE 12 Developing molars Identify : ameloblasts enamel dental papilla odontoblasts gingival epithelium dentine underling alveolar bone 250 µm

  23. SLIDE 12 Developing molars gingival epithelium ameloblasts enamel dentine Identify : ameloblasts enamel dental papilla odontoblasts gingival epithelium dentine underling alveolar bone odontoblasts dental papilla alveolar bone 250 µm

  24. SLIDE 12 Developing molars At a higher magnification, examine the tooth germ and identify the position of : a). ameloblasts. c). enamel. b). odontoblasts. d). dentine. 100 µm

  25. SLIDE 12 Developing molars A A : ameloblasts B : odontoblasts C : enamel D : dentine C D At a higher magnification, examine the tooth germ and identify the position of : a). ameloblasts. c). enamel. b). odontoblasts. d). dentine. B 100 µm

  26. SLIDE 12 Developing molars Describe the shape and organisation of ; ameloblasts. . odontoblasts. 50 µm

  27. Describe the shape and organisation of ; • ameloblasts. A single layer of very long columnar cells, hexagonal in cross . section, with elongated basally sited nuclei. • odontoblasts. Single layer of elongated columnar cells, at dentine-pulp border. SLIDE 12 Developing molars ameloblasts Describe the shape and organisation of ; ameloblasts. . odontoblasts. enamel dentine odontoblasts 50 µm

  28. SLIDE 12 Developing molars What is synthesised by a). ameloblasts? b). odontoblasts? 25 µm

  29. What is synthesised by a). ameloblasts? Enamel. b). odontoblasts? Dentine. SLIDE 12 Developing molars ameloblasts What is synthesised by a). ameloblasts? b). odontoblasts? D E E : enamel D : dentine odontoblasts 25 µm

  30. SLIDE 12 Developing molars From which type of tissue are a). ameloblasts derived? b). odontoblasts derived? 25 µm

  31. SLIDE 12 Developing molars From which type of tissue are a). ameloblasts derived? Epithelium. b). odontoblasts derived? Mesenchyme. 25 µm

  32. SLIDE 12 Developing molars In this picture taken under oil immersion identify the position of Tome’s fibres. What are they? 25 µm

  33. In this picture taken under oil immersion identify the position of Tome’s fibres. What are they? Prismatic extensions of apical cytoplasm. Enamel forming secretions pass through these processes. The ameloblasts move backwards as the enamel layer is secreted. SLIDE 12 Developing molars ameloblasts In this picture taken under oil immersion identify the position of Tome’s fibres. What are they? Tome’s processes enamel 25 µm

  34. SLIDE 13 Developing incisors apical portion of incisor longitudinal section of incisor How do the apical surfaces of this developing incisor tooth differ from the molar? 0.5 mm 250 µm

  35. SLIDE 13 Developing incisors apical portion of incisor longitudinal section of incisor How do the apical surfaces of this developing incisor tooth differ from the molar? The crown of the incisor has only a single cusp, whereas that of the molar may have four, assisting in the grinding of food. 0.5 mm 250 µm

  36. SLIDE 13 Developing incisors A view towards the root of the incisor. Note the reduced height of ameloblast, odontoblast and matrix layers towards the distal end. 0.5 mm 250 µm

  37. SLIDE 13 Developing incisors Identify any spaces between the distinct layers of the developing tooth which you consider to be artefacts. 0.5 mm

  38. SLIDE 13 Developing incisors A2 A1 Identify any spaces between the distinct layers of the developing tooth which you consider to be artefacts. 0.5 mm Traces of enamel can be seen, arrowed, but some has been lost during specimen preparation leaving space artefacts A1. Other artefacts A2 can be seen close to the alveolar bone.

  39. SLIDE 13 Developing incisors Does : a). dentine contain cells? b). enamel contain cells? 100 µm

  40. Does : a). dentine contain cells? No. 70% mineral and 30% collagen and glycoproteins. b). enamel contain cells? No. Composed of crystalline enamel rods. SLIDE 13 Developing incisors ameloblasts enamel (traces of) dentine Does : a). dentine contain cells? b). enamel contain cells? odontoblasts 100 µm

  41. SLIDE 13 Developing incisors What term best describes the process of tooth growth. Is it appositional or interstitial? 50 µm

  42. SLIDE 13 Developing incisors A : space artefact enamel layer indistinct A A What term best describes the process of tooth growth. Is it appositional or interstitial? Appositional. ameloblasts dentine odontoblasts dental papilla 50 µm

  43. SLIDE 13 Developing incisors What is the position of cells most active in the process of matrix synthesis and how do they differ in shape and organisation from cells nearer the proximal end of the tooth? 0.5 mm 50 µm

  44. What is the position of cells most active in the process of matrix synthesis and how do they differ in shape and organisation from cells nearer the proximal end of the tooth? The thickest layers of enamel and dentine (matrix synthesis) are seen at the proximal end of the tooth. Ameloblasts and odontoblasts cells situated towards this proximal end, become more elongated, an indication of greater synthetic activity. SLIDE 13 Developing incisors What is the position of cells most active in the process of matrix synthesis and how do they differ in shape and organisation from cells nearer the proximal end of the tooth? 0.5 mm ameloblasts enamel remnants space artefact dentine odontoblasts 50 µm

  45. Dog head – lateral view ▪ Lower lip removed. Upper lip partially removed, remainder everted to expose partially pigmented labial mucosa. Platysma m. (m. cutaneous facei) partially removed. ▪ Identify : m. temporalis, m. masseter, pinna, auricular cartilage partially covered by parotid salivary gland, mandibular salivary gland, mandibular lymph node, cornea, body of mandible, gingivae, incisor, premolar and molar teeth of upper and lower jaw (which teeth are the carnassials?), root of tongue, parotid duct, (where does this open in the oral cavity?), rami buccales et zygomaticus of facial n, (what structures do these nerves innervate?), spinal n. C2.

  46. SLIDE 14 Serous salivary gland (mouse) Whole section viewed at low magnification. This section also includes some lymphatic tissue. Make sure you can distinguish this. 1.0 mm

  47. SLIDE 14 Serous salivary gland (mouse) SG SG : salivary gland Whole section viewed at low magnification. This section also includes some lymphatic tissue. Make sure you can distinguish this. L : lymphatic tissue L 1.0 mm

  48. SLIDE 14 Serous salivary gland (mouse) Identify : connective tissue capsule, septa; dividing the parenchyma into lobes. duct system. 250 µm

  49. SLIDE 14 Serous salivary gland (mouse) adipocytes ducts Identify : connective tissue capsule, septa; dividing the parenchyma into lobes. duct system. capsule septa lobule lymph node 250 µm

  50. SLIDE 14 Serous salivary gland (mouse) An area from the previous section showing elements of the duct system. Ducts running in the connective tissue septum are termed interlobular ducts. Ducts running within the lobules are termed intralobular ducts. 100 µm

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