Connective Tissue PDF

 State University of Medicine and Pharmacy CONNECTIVE TISSUES Department of histology, cytology and embryology CONNECTIVE TISSUE GENERAL FEATURES 1. Cells 2. Matrix - FIBERS - Ground substance  Note: Connective...

 State University of Medicine and Pharmacy CONNECTIVE TISSUES Department of histology, cytology and embryology CONNECTIVE TISSUE GENERAL FEATURES 1. Cells 2. Matrix - FIBERS - Ground substance  Note: Connective Tissues contain a high ratio of extracellular matrix to cells. extracellular matrix is mostly secreted by cells, which are embedded in it. extracellular matrix varies for different tissues and provides their structural and functional features. Examples : the fluid part of blood the hard part of bone, the tough part of fascia, the resilient part of cartilage.  FUNCTION OF CT MECHANICAL SUPPORT – STROMA BELOW EPITHELIUM METABOLITE EXCHANGE - VASCULAR BEDS ENERGY STORAGE - ADIPOSE TISSUE INFLAMMATION - SITE OF ACTION FOR BLOOD BORNE IMMUNE CELLS FIBROSIS - WOUND HEALING - OVER- PRODUCTION OF COLLAGEN  FUNCTION OF CONNECTIVE TISSUE Mechanical support - stroma below epithelium Epithelium of the epidermis Stroma of the dermis  FUNCTION OF CONNECTIVE TISSUE Metabolite exchange – vascular beds  FUNCTION OF CONNECTIVE TISSUE fat cells Energy storage - adipose tissue skin human breast  FUNCTION OF CONNECTIVE TISSUE Inflammation - site of action for blood borne immune cells  FUNCTION OF CONNECTIVE TISSUE Fibrosis - wound healing - over- production of collagen  Connective Tissue Connective tissues, unlike epithelia, are composed mainly of extracellular elements and a limited number of cells. Found throughout the body; most abundant and widely distributed in primary tissues Embryonic Connective tissue proper Cartilage Bone Blood CONNECTIVE TISSUE CLASSIFICATION mesoderm from the mesoderm  Mesenchymal cells Undifferentiated cells Stellate in shape, Cytoplasmic process, Pluripotent cell Near blood vessels as Advential cell  Embryonic Connective Tissue --- Mesenchyme Consists of cells and ground substance with reticular fibers Gives rise to all types of Connective Tissues CONNECTIVE TISSUE CLASSIFICATION  Note: All Connective Tissues have: Common origin - from mesenchyme Common structure Cells + Extracellular substance Common similar) functions Classification of CT Ratio of cells to fibers Loose (mostly cells) Dense (mostly matrix) Loose (mostly cells) Dense (mostly matrix [ground substance and fibers])  Classification of CT Arrangement of fibers Irregular in dermis and capsules Regular in tendon Irregular Regular Regular Capsule of the testis Tendon Developing Tendon  Classification of CT Origin of cells Fixed Wandering Macrophage Mast cell  Extracellular matrix Parts of the extracellular matrix FIBRILLAR PROTEINS (collagen, elastin) insoluble in water, no hydratation GLYCOPROTEINS (e.g. fibronectin,laminin) GLYCOSAMINOGLYCANS AND PROTEOGLYCANS soluble in water, easily hydratated  Cells of Connective Tissue A. Fixed cells (intrinsic cells) 1.blast & cytes & clasts 2. Mesenchymal cells 3. Adipocyte 4. Fixed macrophages B. Free cells (extrinsic cells/Wandering Cells) 4.Free macrophage 5. Mast cell 6. Plasma cells 7. Leucocytes  Cells of CT Fibroblasts - extracellular matrix synthesis Mesenchymal cells - stem cells Adipose cells - energy storage Macrophage - monocyte linkage Fixed and Wandering Plasma cells - antibody production Mast cells - allergic response Others - lymphocytes, eosinophils Blood cells  Fibroblast Most commonly seen Fusiform with slender cytoplasmic process Large oval nucleus, Responsible for fiber production Mature cells are fibrocyte, Contractile Cells are myofibroblast Fibroblast This electron micrograph of fibroblasts (F) - long, fusiform cells whose processes (p) extend into the surrounding area, between bundles of collagen fibrils. These cells manufacture collagen, reticular and elastic fibers, and the ground substance of connective tissue. Therefore, they are rich in organelles, such as Golgi apparatus (G), rough endoplasmic reticulum (rER), and mitochondria (m);  Adipocytes Store lipid Appears as empty space Incapable to division Aggregate in adipose tissue with reticular fibre Adipocytes (fat cells) function as store house, mechanical support, conservation of body heat. Mobile cells = blood leukocytes Macrophage blood monocyte ps ph er lys  Leucocytes-. Granulocytes- Neutrophils, Esinophils, Basophiles. Agranulocytes Lymphocytes, Monocytes  Macrophages (Histiocytes) Free and Fixed type, Fixed Cells- Irregular Shape filopodia process, Dark indented eccentric nucleus, Derived from monocyte Involved in phagocytosis Fused to form giant cell. Free Cells- rounded, no filopodia  Macrophages in the Normal State Connective tissue (histiocytes) Liver (Kupffer cell) Lung (alveolar macrophage) Lymph nodes (free and fixed macrophages; interdigitation with cell) Spleen (free and fixed macrophages) Bone marrow (fixed macrophage) Macrophages in lymph node  Macrophages in the Normal State Serous cavities (pleural and peritoneal macrophages) Bone (osteoclasts) Central nervous system (CSF macrophages; brain macrophages) Skin (histiocyte (tattoo); Langerhans cell?) Synovia (Type A cell) Other organs (tissue macrophage) Which is/are the real tattoo(s)? Can you read “ USN ” for US Navy? Tattoo after 52 years Macrophage last for 40 years, but how old were your macrophages when you got your tattoo?  Cells of CT Macrophage - monocyte linkage  Plasma cells Oval basophilic cells, Eccentric nucleus Heterochromatin as cart wheel nucleus Derived from B lymphocyte Produces immunoglobulin Antibody collected as Russell body. Present in respiratory tract and gastrointestinal tract  Cells of CT Constitutive secretion Plasma cells - antibody production No granule storage  Mast cell Round or Fusiform Shaped Mostly along blood vessels, Metachromatic granules in cytoplasm, Granules have Histamine or Heparin, Look like basophil, so called as connective tissue basophil. Connective tissue mast cell – heparin granule, present in skin. Mucosal mast cell –small, present in lamina propria of GIT and respiratory tract. Mast cells = basophils  Cells of CT Mast cells - allergic response Mast cell This electron micrograph of a rat peritoneal mast cell displays characteristics of this cell. Note that the nucleus (N) is not lobulated, and the cell contains organelles, such as mitochondria (m) and Golgi apparatus (G). Numerous processes (p) extend from the cell. Observe that the most characteristic component of this cell is that it is filled with numerous membrane-bound granules (Gr) of more or less uniform density. These granules contain heparin, histamine, and serotonin (although human mast cells do not contain serotonin). Additionally, mast cells release a number of unstored substances that act in allergic reactions. Degranulation occurs very quickly but requires both ATP and calcium. Granules at the periphery of the cell are released by fusion with the cell membrane, whereas granules deeper in the cytoplasm fuse with each other, forming convoluted intracellular canaliculi that connect to the extracellular space. Such a canaliculus may be noted in the bottom left-hand corner of this electron micrograph. General components of matrix : 1. Fibers and 2. Ground substance – is a gel containing: water, salts and 3 kinds of molecules containing carbohydrates: glycosaminoglycan or GAG, proteoglycans and glycoproteins Features of ground substance: Glycosaminoglycans: Consistency & viscocity of GS, serves as a physical barrier in spreading infection. Examples: Hyaluronic Acid & Heparan Sulphate. Structural Glycoproteins: Adhesion of cells to the neighbouring cells. Examples: Fibronectin(Dermis), Chondronectin(in Cartilage) & Laminin(in basement membrane) Water & Electrolytes: Maintenance of Fluid balance. Extracellular matrix (ECM)  Types of C. T. Fibers Three types of fibers Collagen fibers Strongest and most abundant Tensile strength > steel Elastic fibers “Yellow fibers” Long, thin, branching fibers Can stretch and recoil Reticular fibers Fine collagenous fibers  Collagen Fibre White colour when fresh Do not branch,wavy present in bundle Collagen protein forms Fibres Fibres composed of fibril made of microfibrils Micro fibrils made up tropocollagen-striations Synthesized by fibroblast Fibroblast is fiber forming cell Steps of the development.  Collagen Tropocollagen is synthesized by Collagen is also synthesized by fibroblasts and released into Chondroblasts: in collagen extracellular space where they get polymerized to form collagen fibrils Osteoblasts : in bone Smooth Muscle: in blood vessels Collagen on boiling gives gelatin Odontoblasts: in the tooth More than 25 types are present  Types Type1-bones ,tendons, dermis etc Type2-cartilage Type3-reticular fibres Type4-basement membrane Type5-blood vessels  Elastic fibre Yellow in color when fresh Composed of elastin protein Singly present Branched and anastomose forming a network Can be stretched (one and a half times) Synthesized by fibroblast and smooth muscle cells in blood vessels Found in ligamentum flava, ligamentum nuchae, large arteries  Reticular fibre Structurally similar to collagen fibres Are very thin Immature collagen fibre Actively branch to form delicate network therefore named Reticular Form supportive framework of lymphoid tissue Stained black by silver salts (argyrophillic) Composed of Collagen Type III Distribution of Connective tissue proper (CTP ) CTP is widely distributed. It forms the capsules of organs and thin septa inside them. It always underlines epithelia. It contains blood vessels and through its ground substance all nutrients and waste products diffuse between the blood and parenchymal cells of all other tissues and organs. Loose irregular connective tissue (L.I.C.T.) Is the most distributed it contains blood vessels The Cells and Fibers of L.I.C.T. Loose Connective Tissue Other types of Connective tissue proper (CTP): Dense Regular CTP Dense Irregular CTP Fibers are predominant elements B. Dense Connective Tissue Regular Irregular Consists of parallel Bundles run in bundles of different direction collagenous fibers Found in inner portion Found in tendons & of skin ligaments Binds organs together Dense Regular Dense Irregular Dense Regular Connective Tissue fibrocyte Collagen fibers form parallel bundles fibrocytes tendons, aponeuroses Tensile strength in one direction Dense Regular Connective Tissue  Dense Irregular Connective Tissue Fibrocyte Collagen fibers are irregularly arranged Tissue can resist tension from any direction Very tough tissue -- dermis of skin Dense Irregular Connective Tissue Dense Irregular Connective Tissue  Connective tissue specialised Adipose: Location – deep to skin: sides, buttocks, breasts; padding around eyeballs and kidneys Function – insulation, mechanical support, stores energy. Reticular: Location – spleen, lymph nodes, bone marrow Function – supporting framework for haemopoietic organs Mucoid: umbilical cord, incompressible Adipose Tissue Reticular Connective Tissue Mucoid Tissue  In summary Blood cells Marrow cells