Oral Histology Update - Prof Simon Whawell (2024-25).pptx

Oral Histology Simon A. Whawell [email protected] Learning objectives At the end of this session and with further study you will: Be able to identify oral tissues and cell types in a histological image Be able to describe how structure relates to function Recognise and...

Oral Histology Simon A. Whawell [email protected] Learning objectives At the end of this session and with further study you will: Be able to identify oral tissues and cell types in a histological image Be able to describe how structure relates to function Recognise and describe changes that occur in oral disease Revise your knowledge of key oral tissues, their development & function Introduction Histology: microscopical study of tissues Fresh tissue rapidly degrades (host & bacterial enzymes) Tissue has to be processed for histology: Fixation e.g. formalin Wax embedding Sectioning Staining Microscopy Introduction – things to bear in mind Stain used Haematoxylin (nuclei) & Eosin (proteins) most common Not always stated if H&E Specialist stains used to highlight certain things e.g. collagen Hard tissues: decalcified or ground section? Orientation/Plane of section Magnification? Colours, intensity & patterns Cells & extracellular matrix (tissue may be mostly ECM) Appearance relates to structure, function, development, physiology Disruption/change in disease Tissues of the oral cavity Hard: Soft: Enamel Pulp Dentin Gingiva Cementum Periodontal ligament Bone Oral mucosa Temporomandibular Salivary glands joint Remember: tissues found elsewhere in the body present too e.g. blood vessels, nerves, muscle etc. Tooth development Complex highly regulated process Multiple specialised cell types Stages can be recognised using histology Teeth: ground section Enamel & dentin (& bone) are mineralised hard tissues Traditional histological processing cannot be performed Either: Ground section – tissue is sawn and then polished until thin enough to see microscopically Decalcified – mineral is removed using acid until the specimen is soft enough for standard processing Teeth: decalcified section  Dental Pulp ‘Loose’ connective tissue Capillaries & nerves Extracellular matrix: Collagen I & II Proteoglycans Cells: Fibroblasts Odontoblasts Stem/undifferentiated mesenchymal cells Lymphocytes Plasma cells Macrophages Periodontal ligament Connective tissue anchoring tooth to alveolar bone Principle & Sharpey’s fibres: bundles of collagen I & III Blood vessels & nerves Cells: Fibroblasts Osteoblasts & clasts Cementoblasts & clasts Epithelial rests of Malassez Macrophages Stem cells Gingiva Bone Compact/cortical bone – dense Haversian system/osteons Trabecular/spongy/ cancellous bone Loose network of bony struts Woven bone - immature Temporomandibular joint Oral mucosa Keratin Granular Stratified Prickle/Spinous squamous epithelium Lining (Buccal, labial) Basal Masticatory (hard palate, attached gingiva, dorsum of tongue Specialist (taste buds) Varying amounts Specialist mucosa Lingual papillae on the dorsum of the tongue Filliform: keratinised, mechanical role Fungiform: lateral border, some taste buds Curcumvallate: lots of taste buds Von Ebner’s serous glands open into cleft Lip Salivary glands Parotid, Sublingual, Submandibular, Minor Mucous acini stain more weakly (lighter) due to the tissue processing Salivary glands Sublingual Submandibular Parotid Oral disease I Oral Disease II Oral disease III Summary Cells and extracellular matrix visible in detail Pattern indicates type of tissue and therefore types of cells present Structure (always)=function Different in disease (histopathology), can be used for diagnosis, prognosis & treatment planning Images make good exam questions! Resources University of Michigan histology & virtual microscopy https://histology.medicine.umich.edu/resources/oral-cavi ty University of Leeds Oral histology: https://www.histology.leeds.ac.uk/oral/ Books/DLE: Ten Cate’s Oral Histology, Wheater’s Functional Histology 1 A B. C D E 2. } A B C D E 3. 4. 5. When you have covered it. A D B E C