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Skeletal tissue.pdf
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- 2. To outlinethe classification of cartilage tissue with examples. To state the differences of the different types of cartilage. To describe the arrangement of cells and matrix in bone. Objectives – Cartilage & Bones
- 3. Bone & Cartilage specialized type of connective tissue adapted to bear weight provide rigidity necessary for the supporting framework of the body.
- 4. • Development -primitive mesenchyme • structural and functional differences are related to the nature the proportion of the ground substance the fibres in the extracellular matrix. Bone & Cartilage
- 5. Bone & Cartilage Cartilage– semi rigid nature predominant ground substance joints walls of thorax larynx, trachea bronchi, nose and ears. Bone- mineralized extracellular matrix
- 6. • chondro refersto cartilage – chondrocyte – Perichondrium • osteo refers to bone – osteogenesis – osteocyte – Periostium • blast refers to precursor cell or one that produces something – Osteoblast • cyte refers to cell – osteocyte Terms
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- 8. Cartilage Cartilage comprise of cells- Chondrocytes ground substances fibres Covered with fibrovascular membrane – Perichondrium outer fibrous layer Inner chondrogenic & vascular layer Growth of cartilage Appositional growth – surface deposition of cells of inner perichondrial layer Interstitial growth – multiplication of cells situated within the matrix of the cartilage. Intercellular matrix
- 9. Nutrition of Cartilages No capillary blood supply of its own 2 ways Diffusion from capillaries in the adjoining connective tissue Synovial fluid from joint cavities
- 10. Cartilage cells Youngcartilage cells – chondroblasts smaller in size irregular in shape Mature cartilage cells – chondrocytes in spaces of matrix/lacunae single cells – spherical shape cell nest (2-4 cells) – D shape large, rounded nuclei basophilic cytoplasm stained section : shrinkage artifact
- 11. Cartilage – fibres Thick collagen fibres Branching and anastomosing elastic fibres Cartilage – ground substances Amorphous gel like substance Stained in basic dye due to chondroitin sulphates & keratosulphates Deep basophilic rim called capsular territorial matrix & stains darker than the interterritorial matrix.
- 12. Based on thevisibility and nature of fibres in the ground substances – hyaline cartilage – white fibro cartilage – yellow elastic cartilage. Classification of Cartilage
- 13. 2 varieties Costal cartilage Present at the ends of growing bones, ribs & respiratory passages Covered by perichondrium Articular cartilage Present at articular ends of the bones (most synovial joints) No perichondrium covering H &E : Homogenous basophilic matrix Collagen type 11 fibres. Fibres not seen as a distinct entity cell nest Hyaline Cartilage
- 14. Hyaline Cartilage Red arrowindicates the Perichondrium. Black arrow indicates the chondroblasts. Yellow arrow indicates the chondrocytes in lacuna
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- 16. Yellow Elastic Cartilage Elasticity network of branching and anastomosing elastic fibres in its ground substances Present in Pinna, epiglottis, external auditory meatus, arytenoid , corniculate & cuneiform cartilage In fresh state – yellowish colour Large chondrocytes single or small groups chondrocytes Perichondrium present Collagen type 11 fibres
- 17. Yellow Elastic Cartilage Blackarrow – perichondrium Red arrow – cartilage
- 18. Yellow Elastic Cartilage Yellowarrow – chondrocytes in lacunae Black arrow – cartilaginous matrix pink and not homogenous
- 19. similar tohyaline cartilage except that - excessive amounts of collagen fibres in the EC matrix Parallel bundle of type 1 collagen fibres Chondrocytes lie singly & smaller number Chondrocytes arranged in rows. present in intervertebral discs, pubic symphysis & intra-articular discs Perichondrium is absent in adult fibrocartilage White fibrocartilage
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- 25. Support Movement Protection Mineral storage Blood cell formation and energy storage Functions of Bones
- 26. 2 mainforms woven bone (primary bone ) lamellar bone (secondary bone ) Woven bone : Newly formed bone , no layers/lamellar Collagen fibre bundles run randomly in different direction found in the foetus, tooth sockets ,sutures in repair of fractures Lamellar bone: compact or dense bone cancellous or spongy bone Bones
- 27. network ofnarrow irregular bars or trabecullae enclosing large intercommunicating spaces filled with bone marrow. solid dense mass spaces are small and cannot be seen with the naked eye. Compact bone Cancellous (spongy bone)
- 28. Macroscopic appearance A typicallong bone (humerus. radius) cut longitudinally- shaft- diaphysis hollow cylinder of compact bone trabeculae of spongy bone - inner surface marrow cavity with yellow marrow Epiphysis- spongy bone- spaces between the trabeculae contain red marrow continuous with the medullary cavity
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- 30. 2 layers. outerlayer- dense connective tissue collagen and elastic fibres blood vessels and nerves inner layer - loose connective tissue. more cellular during growth this layer contains osteogenic cells- osteogenic layer Periosteum
- 31. vascular membrane has the potential to form bone during bone growth and healing. easily stripped off in young bones In adult bones - firmly adherent particularly at the site of insertion of tendons and ligaments. Periosteum
- 32. periosteal fibrespenetrate the surface layers of the bone as perforating fibres of Sharpey Nutrients reach the bone through vessels that enter through the nutrient foramina. Periosteum
- 33. arrangement ofthe bone matrix – layers / lamellae. Small ovoid spaces - lacunae (between and within the lamellae) contain a single bone cell - osteocyte radiating from lacunae- canaliculi join up with canaliculi of adjacent lacunae. canaliculi contain the processes of cells Microscopic appearance - Bone
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- 35. unit structureof the bone. most of the lamellae are cylindrical units run parallel to the long axis of the bone. each osteone consists of 8 to 15 concentric lamellae around - Haversian canal it contains a neurovascular bundle. osteones appear round or oval in transverse section. Haversian systems or osteones
- 36. haversian canalscommunicate with each other by oblique and transverse channels. communicate with the periosteal and endosteal surface by Volkman’s canals blood vessels communicate with those of marrow cavity via those canals canaliculi open into Haversian canals lacunae communicate with Haversian canal. Haversian systems or osteones
- 37. Haversian systems orosteones
- 38. Lamellae may showthree different patterns Haversian systems or osteones Interstitial lamellae Circumferential lamellae Compact bone
- 40. In betweenthe osteones are irregular areas of lamellae bone Osteones and interstitial lamellae- demarcated from neighbouring systems by a strongly basophilic cement line or reversal line it is not traversed by canaliculi. Interstitial lamellae
- 41. Outer circumferentiallamellae lies immediately beneath the periosteum extend almost completely around most of the shaft of the bone Inner circumferential lamellae a less developed system of lamellae lines the endosteum Circumferential lamellae
- 42. Osteon Endosteum Haversian canal Volkmann’s canal Helical courseof collagen Inner circumferential lamellae Outer circumferential lamellae
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- 44. bony plates/ rods that forms the meshwork = trabeculae trabeculae and spicules are thin not traversed by blood vessels & receives nutrition from blood vessels in the bone marrow no osteones & contains fragments of lamellar bone Cancellous Bone
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- 46. Osteoprogenitor cells Osteoblasts Osteocytes Osteoclasts Cells of Bone
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- 53. REFFERENCES Burkit, H.G,young, B. (1993). Wheaters functional histology. 4 th ed., london:Churchill livingstone Junqueira, L.C., Carneiro (1998). Basic histology. 9 th ed., stamford: Appleton & lange