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CONNECTIVE TISSUES . JANUARSIH I.A.RACHMAN. Learning Objectives. To define the microstructure of connective tissue proper To define the microstructure of connective tissue with special properties To define the microstructure of supporting connective tissue . Three fundamental components :
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CONNECTIVE TISSUES JANUARSIH I.A.RACHMAN
Learning Objectives • To define the microstructure of connective tissue proper • To define the microstructure of connective tissue with special properties • To define the microstructure of supporting connective tissue
Three fundamental components : - cells - protein fibers : Collagens, elastic - ground substance
Connective Tissue spread 1. Elastic fibers 2. Collagenous fiber 8. Fibroblasts 3. Adipose cells 9. Collagenous fibers 10. Elastic fibers 4. Fixed macrophages (histiocytes) 5. Eosinophils 11. Fixed macrophages 6. Lymphocytes 7. Mast cells 12. Capillary containing erythrocytes 13. Cytoplasmic processes 16. Nucleus 18. Nucleus 14. Nucleus 19. Mast cell granules 15. Nucleolus 17. Vacuoles with neutral red I. Fibroblast II. Fixed macrophage III. Mast cell
Cells Fixed cells : • Fibroblast ( the predominant cells) • Mesenchymal cells • Reticular cells • Adipose cells ( adipocytes, fat cells )
Wandering cells • Mast Cells • The granules, which often obscure the small central nucleus contain heparin, histamine and eosinophil chemotactic factor of anaphylaxis (ECF-A) • Mast cells have surface receptor for the Ig E antibodies that trigger degranulation • Allergic reactions
Wandering cells (cont.) • Macrophages are large stellate cells • Plasma cells • Other blood - derived connective tissue cells • Leukocytes ( i.e. Lymphocytes, neutrophils, eosinophils and basophils
Connective Tissue 7. Adipose cells 8. Nuclei of adipose cells 1. Collagenous fibers 2. Fibroblast nucleus 9. Collagenous fibers 3. Fibroblast nuclei 4. Fibroblast : cytoplasm and nucleus 10. Capillaries 11. Neutrophil 5. Neutrophil 12. Lymphocytes 6. Lymphocyte Loose connective tissue
Connective Tissue 1. Tendon cells 4. Nuclei of tendon cells (surface view) 2. Collagenous fibers 4. Nuclei of tendon cells (slide view) 3. Bundle of tendon fibers Dense regular connective tissue
Connective Tissue 7. Skeletal muscle fibers (t.s) 1. Bundles of tendon fibers 8. Interfascicular connective tissue 2. Tendon cells (nuclei) 3. Connective tissue between bundles 4. Interfascicular connective tissue 9. Tendon cells 5. Blood vessels 6. Lamellar (Pacinian corpuscle) 10.Collagenous fibers Dense regular connective tissue
Dense irregular connective tissue The component of this tissue are identical to those in dense regular connective tissue 6. Perivascular undifferentiated Mesenchymal cell 1. Bundles of tendon fibers 7. Endothelial cell 2. Collagenous fibers (l.s) 8. Venule 9. Lymphocytes 10. Elastic fibers 3. Neutrophils 4. Capillaries 11. Fibroblasts 5. Fibroblasts Dense irregular arranged connective tissue
Connective Tissues with Special Properties Reticular Connective Tissue :
Mucous Connective Tissue This tissue has few cells and fibers distributed randomly in the abundant ground substance (Wharton’s jelly)
Adipose Tissues The two types of adipose tissues • Unilocular adipose tissue (common, yellow) • Multilocular adipose tissue (brown)
Development of fat cells. Undifferentiated Mesenchymal cells are transformed into lipoblasts that accumulate fat and thus give rise to mature fat cells. When a large amount of lipid is mobilized by the body, mature unilocular fat cells return to the lipoblast stage. Undifferentiated mesenchymal cells also give rise to a variety of other cell types, including fibroblasts. The mature fat cell is actually larger than shown here in relation to the other cell types in this illustration.
Unilocular Adipose Tissue • also termed as White/yellow adipose tissue • single fat droplet → a signet-ring appearance
Multilocular Adipose Tissue • Feature : • - Brown fat • - multiple small lipid droplets in its adipocytes. • Brown adipocytes are smaller than white adipocytes, a spherical and central nucleus, • numerous mitochondria • Distribution : • Newborns
Composed of : • Fibers – mostly thin fibrils at type II collagen • Ground substance : - - - Glycosaminoglycans - Proteoglycans : chondroitin 4-sulfate, chondroitin 6-sulfate, keratan-sulfate, linked to core protein Proteoglycans associated with long molecules of hyaluronic acid, forming proteoglycans aggregate - Glycoprotein : chondronectin and Tissue fluid • Cells : Chondroblasts & Chondrocytes
The three types of cartilage • Hyaline cartilage • Elastic cartilage • Fibrocartilage
Growth Cartilage grows by 2 distinct processes • a. Interstitial growth • Resulting from the mitotic division of preexisting chondrocytes • b. Appositional growth • Resulting from the differentiation of perichondrial cells
Composed of : • Bone Matrix • Cells : • Osteocytes • Osteoblasts • Osteoclasts • Osteoprogenitor
Bone matrix (cont.) • INORGANIC MATTER • Calcium Phosphate • Bicarbonate • Citrate • Magnesium • Potassium • Sodium • ORGANIC MATTER • Collagen Fibers • Amorphous Ground substance : • Chondroitin 4-sulfate • Chondroitin 6-sulfate • Keratan Sulfate
Mesenchyme Osteoclast Newly formed matrix Osteocyte Osteoblast Bone Matrix Cells
Histogenesis • Intramembranous Ossification • Endochondral Ossification
Bone Blastema Primary bone Tissue Mesenchyme The beginning of intramembranous ossification
Endochondral Ossification • Resting zone • Proliferative zone • Hypertrophic cartilage zone • Calcified zone • Ossification zone
TYPE OF BONE • MICROSCOPIC EXAMINATION • Primary, immature or woven bone • Secondary, mature or lamellar bone • GROSS OBSERVATION (CROSS SECTION) • Dense area without cavities : Compact Bone • Areas with numerous interconnecting cavities : Cancellous (spongy) bone • ANATOMY • long bone • short bone • flat bone
Thick ground section of tibia illustrating the cortical compact bone and the lattice of trabeculae of cancellous bone
PRIMARY BONE TISSUE (immature, woven bone) • First bone tissue • Temporary, replace by secondary bone tissue, except : • Near the sutures of the flat bones of the skull • In tooth sockets • In the insertion some tendons • Characteristics : • Irregular array of collagen fibers • Smaller mineral content • Higher proportion of osteocytes than in secondary bone tissue
SECONDARY BONE TISSUE (mature, lamellar bone) • Usually found in adults • Characteristics : • - Haversian system or osteon • Lacunae • Haversian canals • Cementing substance • Collagen fibers : Lamellae • The lamellae exhibit a typical organization consisting of • Haversian system • Outer circumferential lamellae • Inner circumferential lamellae • Interstitial / intermediate lamellae
Interstitial lamellae Haversian system (osteon) Inner Circumferential lamellae Outer circumferential lamellae Volkmann’s canal Haversian canal Periosteum Endosteum
Periosteal proliferation Newly formed primary bone Periosteum Bone Callus Newly formed secondary bone Hyaline Cartilage Healed fracture Fracture Repair
The Periosteum and endosteum proliferation of osteoprogenitor cells Formed a cellular tissue Bone is formed by endochondral and intramembranous ossifications Formed Trabeculae of primary bone (A Bone Callus) The callus is gradually resorbed and replaced by secondary bone
Now I know • the microstructure of connective tissue proper • the microstructure of connective tissue with special properties • the microstructure of supporting connective tissue