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Connective Tissue

Connective Tissue. Dr. Ashraf Hussain. Connective Tissue. These tissues connect and support other tissues of the body. Connective Tissue. Mechanical support Medium for exchange of nutrients & waste products Energy store and thermal insulation Defensive functions

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Connective Tissue

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  1. Connective Tissue Dr. Ashraf Hussain

  2. Connective Tissue • These tissues connect and support other tissues of the body

  3. Connective Tissue • Mechanical support • Medium for exchange of nutrients & waste products • Energy store and thermal insulation • Defensive functions a) Barrier b) Engulf bacteria c) Antibodies

  4. Connective tissue • Connective tissue comprises a diverse group of cells embedded in a tissue-specific extracellular matrix • Different type of connective tissue are responsible for a variety of functions • Classification of connective tissue is based on the composition and organization of its cellular & extracellular components and on its functions

  5. Structure of connective tissue • Cells • Intercellular substance or matrix

  6. Matrix • Amorphous ground substance • Thread like formed elements called fibers (collagen fibers, reticular fibers, elastic fibers) • Tissue fluid

  7. Cellular component interspersed in intercellular substance different kinds of cells Fibers – part of the “formed substance” of C.T. embedded in ground substance Matrix = ground substance + fibers

  8. Resident cell population Fibroblasts Macrophages Adipose cells Mast cells Undifferentiated mesenchymal cells Wondering cell population Lymphocytes Plasma cells Neutrophils Eosinophils Basophils Monocytes Connective tissue cells

  9. Leucocytes in loose supporting tissueF-Fibroblasts, Er-Erythrocytes, N-Neurtrophils, Eo-Eosinophils, L-lymphocytes, P-Plasma cells, M-Macrophages

  10. Connective tissue cells • Fibroblasts • Histiocytes (Macrophages) • Plasma cells • Mast cells • Fat cells

  11. ADULT CONNECTIVE TISSUE COMPONENTS Connective Tissue Cells

  12. Connective tissue cells Fibroblasts Most abundant Appearance varies in relation to functional state Produce connective tissue fibers & secrete ground substance

  13. Mature Fibroblasts

  14. Active fibroblasts

  15. Histiocytes (Macrophages) • Abundant • Inactive and active histiocytes • Scavenger cells • Foreign body giant cells • Antigen presenting cells

  16. Macrophage

  17. Plasma cells • Generally rare but numerous at certain sites e.g., intestinal mucosa, lymphoid organs • Nucleus—cart wheel appearance • Production of antibodies

  18. Mast cells • Mast– well fed (German) • Abundant in loose connective tissue around blood vessels • Secrete Heparin ( anticoagulant) & Histamine (vasodilator)

  19. Mast Cells

  20. Fat cells (adipocytes) • Form adipose tissue when accumulate together • Signet ring appearance

  21. Blue dotted lines - Adipocytes • Orange Arrows - Fat droplet "space" • Green Arrow - Nuclei of Adipocyte

  22. Connective tissue fibers • Long slender protein polymers which are found in differing proportions in various types of connective tissue • Predominant fiber type is responsible for conferring specific properties to the tissue

  23. Connective tissue fibers • Collagen fibers --collagen • Reticular fibers --collagen • Elastic fiber -------elastin

  24. Collagen • Long molecule—tropocollagen • Three polypeptide chains intertwined together— triple helix • By now 19 varieties of collagen have been identified • Most important & best studied are I,II, III, IV &V.

  25. Growth of molecular character of a collagen fibril

  26. Collegen fibers are most abundant type of connective tissue fibers • Collagen fiber formation involves events that occur both within and outside the fibroblast

  27. Collagen fibers • Diameter (2-10 micrometer) • Run randomly in various directions • In many parts, collagen fibers lie parallel to each other forming bundles of various sizes • Flexible but inelastic (non-extensible) • Pink colour with H&E stain

  28. Blue arrow - Collagen BundleGreen Arrow - Fibroblast nuclei

  29. Reticular fibers • Reticular fibers provide a supporting framework for the cellular constituents of various tissues and organs • Reticular fibers are named for their arrangement in a mesh-like pattern or network

  30. Reticular fibers • Very thin branching fibers (rete—net) • Diameter (0.5 to 2 micrometer) • Coating of proteoglycans & glycoproteins– black colour with silver staining, red with PAS • Abundant in connective tissue around muscle fibers, nerve fibers, acini of glands, lymphoid organs & bone marrow

  31. Elastic fibers • Highly elastic can stretch one and half time their original length • Diameter (0.2 to 1.0 mic.m) • Branch & rejoin to form loose network • Found in lungs, large arteries, ligamenta flava (connecting laminae of successive vertebrae)

  32. Elastin fibres

  33. Ground substance • Ground substace occupies the space between the cells and fibers • Ground substance consists largely of proteoglycans and hyaluronic acid • Proteoglycans and Glycosaminoglycans (GAG) are responsible for the physical properties of ground substance

  34. Embryonic connective tissue • Develops from mesoderm & is known as Mesenchyme • Composed of star-shaped cells which lie in an abundant relatively homogeneous intercellular substance • Mucous tissue– Wharton’s jelly

  35. Arrows = cells in mitosis; “C” = small blood vessels; Ground substance devoid of fibers; Cell processes extend into homogeneous ground substance

  36. Disorders of connective tissue • Marfan syndrome - a genetic disease causing abnormal fibrillin • Scurvy- dietary deficiency in Vit.C leading to abnormal collagen. • Ehlers-danlos syndrome - a genetic disease causing progressive deterioration of collagens affecting different sites in the body such as joints, heart valves & arterial walls

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