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Connective TissueConnective Tissue
Different types of connective tissues maintain form of the body by providing the matrix which connects and bind cells and organs of the body.
Connective tissue consists of:
Cells
Fibers
Ground substance Wide variety of connective
tissue types reflects variation
in the composition and the
amount of the three
components
Cells Cells
of the of the
Connective TissueConnective Tissue
Fibroblast Most dominant cell type of connective tissue Synthesis of extracellular matrix components Synthesis of fiber proteins Production of growth factors Fibroblast features Fibrocyte features
MacrophageMacrophage
Ultrastructural featuresUltrastructural features Derived from monocyteDerived from monocyte They form the Mononuclear They form the Mononuclear
Phagocyte SystemPhagocyte System Kupffer cell, Microglia, Osteoclast,Kupffer cell, Microglia, Osteoclast,
Langerhans cell, dendritic cell, Langerhans cell, dendritic cell, Multinuclear giant cell, Epitheloid Multinuclear giant cell, Epitheloid
cellcell FunctionsFunctions
Mast CellMast Cell
Ultrastructural featuresUltrastructural features Secretory granules and contentSecretory granules and content MetachromasiaMetachromasia FunctionFunction TypesTypes
Connective tissue mast cellConnective tissue mast cell
Mucosal mast cellMucosal mast cell
Plasma CellPlasma Cell
Ultrastructural featuresUltrastructural features OriginOrigin FunctionFunction
Adipocytes and Leukocytes
Will be described later. Adipocytes is a connective tissue cell
specialized in fat storage and heat production Leukocytes leave the blood stream by
Diapedesis. They release chemical mediators of inflammation.
Fibers Fibers
of theof the
Connective TissueConnective Tissue
Collagen Fibers
Made of collagen protein which constitutes 30% of human body
They form a family of >25 produced by different types of cells
Classifications:Collagen forming long fibrils I, II, III, V, XIFibril-associated collagen IX, XII, XIVCollagen forming anchoring fibrils VIICollagen forming network IV
Made mainly of glycine and proline
Reticular FibersReticular Fibers
Made of collagen type III They are very thin and form an extensive net
work in certain organs They contain 6-12% hexose sugars They are found in parenchymatous
organs e.g. liver and spleen Argyrophilia, PAS +
Elastic FibersElastic Fibers
A system consists of Oxytalan, Elaunin, and Elastic fibers.
Oxytalan fibers are not elastic but resistant to pulling e.g. zonular ligament and dermis. Consists of fibromodulin and fibrillin
Elaunin fibers: elastin start to deposit between oxytalan fibers e.g. around sweat glands and dermis
Elastic fibers: rich in elastin surrounded by a sheath of microfibrils of oxytalan
Made of, in addition to glycine and prolin, desmosine and isodesmosine
Ground Substance
Consists of hydrated , colorless, transparent mixture of macromolecules.
It acts as a lubricant and a barrier Composed of:
Glycoseaminoglycans
Proteoglycans
Glycoproteins
Glycoseaminoglycans
Composed of linear polysaccharides formed of repeating disaccharides units made of uronic acid and hexosamine
They are intensely hydrophilic and basophilic and acts as polyanion due to OH ,COO, and SH groups
Types and distribution
Hyaluronic Acid Chondroitin sulfate Dermatin sulfate keratin sulfate
Proteoglycans
Consists of a core protein to which different types of glycosaminoglycan are attached except hyaluronic acid
Some are free in the ground substance e.g. Aggrecan and others
are attached to cell
membrane e.g.
Syndecan
Fibroglycan
GlycoproteinsGlycoproteins
Made dominantly of protein to which attached abranched carbohydrates
Plays a role in the interaction between adult and embryonic cells and adhesion of cells into their sustrate
Examples
Fibronectin
Laminin
Types of Connective TissueTypes of Connective Tissue
Connective tissue properConnective tissue proper
Loose connective tissueLoose connective tissue
Dense connective tissueDense connective tissue
RegularRegular
IrregularIrregular
Connective Tissue with Special Connective Tissue with Special PropertiesProperties
Adipose Tissue Elastic Tissue Hematopoietic Tissue Mucus Tissue Reticular tissue
Adipose Tissue
A special type of connective tissue in which adipocytes predominate
It serves as energy depot It shapes the body Act as a shock absorber Thermal insulation Keeps some organs
in place e.g. Kidney
Unilocular (Yellow) adipose Tissue
It is white to yellow because of carotenoids Most common in adult Almost found everywhere in the body Distribution is affected by age and sex Adipose tissue is divided into incomplete
lobules by connective tissue It is richly vascularized Leptin is produced by fat cell to regulate
amount of adipose tissue in the body Ultrastructure of the adipose cell
Multilocular (Brown) Adipose Tissue
It is brown because of richness of capillaries and numerous mitochondria containing colored cytochromes
It has a localized distribution Ultrastructure of adipose cell Cells are directly innervated
by sympathetic nerves
Clinical Applications
Immediate hypersensitivity reaction and Anaphylactic shock
Progressive systemic sclerosis and keloid Marfan syndrome and fibrillin gene mutation Ehlers-Danlos IV, VI, VII, Scurvy, Osteogenesis
imperfecta