Connective tissue histology

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Connective / Supporting tissues: 

Connective / Supporting tissues Dr Pankaj Maheria 1 Dr Pankaj

Objective : 

Objective At the end of this learning session you would be able to Enumerate the characteristics of connective tissue List the cells found in CT Describe the components of Areolar tissue as a Prototype CT Distinguish between Dense regular, Irregular CT Elastic CT Reticular CT Dr Pankaj 2

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A basic type of tissue of mesoderm origin which provides structural and metabolic support for other tissues and organs throughout the body. 3 Dr Pankaj

General function : 

General function Support the organs and cells Act as medium for exchange of nutrients and wastes between the blood and tissues Protects against microorganisms Repair damaged tissue Storage Packing 4 Dr Pankaj

Classification : 

Classification Connective tissue proper Loose connective tissue Dense connective tissue Irregular Regular Elastic and reticular connective tissue Elastic tissue Reticular tissue 5 Dr Pankaj

Classification : 

Classification Specialized connective tissue Adipose tissue Cartilage Bone Blood Hemopoietic tissue Lymphatic tissue 6 Dr Pankaj

Classification : 

Classification Embryonic connective tissue Mesenchymal tissue Mucous connective tissue 7 Dr Pankaj

Components of support tissue: 

Components of support tissue Support cells Extracellular matrix Ground substance Extracellular fibres Dr Pankaj 8

Extracellular matrix : 

Extracellular matrix Dr Pankaj 9

Fibres of supporting tissue: 

Two main type Collagen ( including reticulin which was formerly considered a separate fibre type) Elastin Dr Pankaj 10 Fibres of supporting tissue

Collagen : 

Main fibre type found in most supporting tissue. Most abundant protein in the human body function : provision of tensile strength Classified by roman numerals on the basis of the chronology of their discovery. 27 different types Type I and IV are the most abundant. Dr Pankaj 11 Collagen

Collagen : 

Do not branch Run in wavy course. White in color when fresh Each collagen fibres consist of small parallel fibrils. Each fibils consist of bundle of parallel microfibrils which show cross striations. Dr Pankaj 12 Collagen

Collagen : 

Secreted into the extracellular matrix in form of tropocollagen Tropocollagen is about 260 nm long and 1.5 nm thick Three polypeptide chain called alpha units. Synthesized by fibrobalst When boil become gelatin Dr Pankaj 13 Collagen

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14

Collagen : 

Type Place function Type I Dermnis of skin, tendons, ligaments and bone Resistance to force, tension and strech Type II Hyaline cartilage Resistance to press Type III Reticulin Liver, bone marrow and lymphoid organs Structural support and elasticity, internal reticular framework of parenchyma Type IV Basement membranes Physical support ,filtration barrier Type VII Basement membranes Anchor cells, large collagen fibrils , Dr Pankaj 15 Collagen

Elastic fibres: 

Composed of protein called elastin Synthesized by fibroblast and smooth muscles cells (Blood vessles ) Fibres are single and not in bundle Branch and anastomose forming a network. Can be stretched Yellow in colour when fresh Found in ligament nuchae , ligament flava , large artery Dr Pankaj 16 Elastic fibres

Ground substance : 

It is a transparent , homogeneous , viscous solution. Fills the space between cells and fibers. Acts as a molecular sieve facilitating diffusion of metabolites between blood and tissues. Dr Pankaj 17 Ground substance

Ground substance : 

Compozition Mucopolysaccharides Consistency and viscocity Act as physical barrier to spread of infection. Structural glycoproteins Adhesion of cells to neighboring structures. Water and electrolytes Maintenance of fluid blance . Dr Pankaj 18 Ground substance

Cells: 

Cells 19 Fixed cells Fibroblast Adipose cells Pericytes Mast cells Macrophages Transient cells Plasma cells Lymphovytes Neutrophils Eosinohils Basophils Macrophages

Fibroblast : 

Fibroblast Dr Pankaj 20 Fibroblast , the most abundant cell type in the connective tissue, are responsible for the synthesis of almost all of extracellular matrix.

Fibroblast: 

Fibroblast Dr Pankaj 21 Aries from mesenchymal cells Predominant cells in connective tissue proper Often have an oval nucleus with two or more nucleoli

Fibroblast: 

Fibroblast Dr Pankaj 22 Rarely undergo mitosis except in wound healing May differentiate into other cell type under certain condition Responsible for formation of fibres and ground substance Often associate with collagen fibres

Fibroblast : 

Fibroblast Dr Pankaj 23 Two type Active Quiescent (Inactive) Spindle shaped Contain well developed rough endoplasmic reticulum and many golgi complex Synthetically active Produce procollagen and othe componate of extracellular matrix Small and flattened cells Contain little rough endoplasmic reticulum Synthetically inactive Revert to active state if stimulated

Primitive mesenchymae: 

Primitive mesenchymae Dr Pankaj 24 Embryological tissue from which all type of supporting tissue , including that of the skeleton are dervied Some cells remain in fully mature supporting tissue and act as stem cells Irregular, star or spindle in shape with delicated branching cytoplacmic processes Oval nuclei have isolated chromatin and visible nucleli Circulatory system of embyo is poorly developed untill a late stage and mesenchyme permits free diffusion of metabolites to and from developing tissue

Pericytes : 

Pericytes Dr Pankaj 25 Derived from embryonic mesenchymal cells May returns to pluripotential role Charateristics of endothelial cells as well as smooth muscle cells because they contain actin , myosin and tropomyosin , suggesting that they have may function in contraction Smaller than fibroblast

Pericytes : 

Pericytes Dr Pankaj 26 Location Mostly alone capillaries, yet they lie within their own basal lamina Function Modify capillary blood flow. During blood vessel formation and repair they may differentiated into smooth muscle cells as well as endothelial cells.

Fat cells (Adipocytes): 

Fat cells ( Adipocytes ) Dr Pankaj 27 Aries from mesenchymal cells and perhaps from fibroblast Do not normally undergo cell division Increase in number in early neonatal life Store energy

Fat cells (Adipocytes): 

Fat cells ( Adipocytes ) Dr Pankaj 28 Large cell 50 µm Each cell contains a large single lipid drop let which is dissolved by xylol during preparation of section, leaving a large empty space and athin rim of cytoplasm and peripheral nucleus- ring Supported by reticular fibrous

Fixed macrophages or histiocytes: 

Fixed macrophages or histiocytes Dr Pankaj 29 Irregular in shape with numerous filopodial processes. Nucleus :Dark eccentrically placed irregular with heterochromatin typically clumped around nuclear envelope. Acidophilic cytoplasm containing many lysosomes .

Fixed macrophages or histiocytes: 

Derived from blood monocytes . Principal phagocytosing cells of connective tissue. Involved in phagocytosis – play a role in local defence of the body against bacterial invasion Form part of mononuclear phagocytic syatem Can be stain with vital dyes Fixed macrophages or histiocytes Dr Pankaj 30

Fixed macrophages or histiocytes: 

Active B lymphocytes to from antibodies Multinuclated giant cells Receives different names depending on its location Kupffer cells — liver Mesangial cells — kidney Microglia — central nervous system Fixed macrophages or histiocytes Dr Pankaj 31

Free macrophages : 

Free macrophages Dr Pankaj 32 During antigenic stimulation or inflammation fixed macrophages withdraw their processes and become free macrophages.

Mast cells: 

Mast cells Dr Pankaj 33 Aries from myeloid stem during hemopoiesis Reside near small blood vessels Largest cells of connective tissue Round or fusiform cells with centrally place rounded nucleus

Mast cells: 

Mast cells Dr Pankaj 34 Cytoplasm filled with water solube basophilc granules They have property of Metachromasia

Mast cells: 

Mast cells Dr Pankaj 35 These granules contain histamine, a vasodilator and heparin Functionally they resemble blood basophils so often called connective tissue basophils .

Plasma cell: 

Plasma cell Dr Pankaj 36 Antibody manufacturing cells Aries from activated B lymphocytez Reposnsible for humoral immunity Ovoid cells contain eccentric nucleus possing clumps of heterochromatin , which appear to be arranged in a wheel spoke fashion.

Plasma cell: 

Plasma cell Dr Pankaj 37 Cytoplasm is deeply basophilic because of an abudant of rER A prominent area adjacent to the nucleus appears pale and contain the golgi complex. Found more in lamina propria of GIT and respiratory tract. Russell’s body

Leucocytes : 

Leucocytes Dr Pankaj 38 Nucleated WBC which migrate to connective tissue from blood vessels Found in large number during inflammatory condition. Perform phagocytosis or cell mediate immune response to specific foreign material or pathogens

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Dr Pankaj 39

Loose areolar connective tissue : 

Loose areolar connective tissue Dr Pankaj 40 Few loosely arranged collagen and elastic fibres . Large number of connective tissue cells Large amount of ground substance

Dense regular connective tissue: 

Dense regular connective tissue Dr Pankaj 41 Bundles of parallel collagen fibres Row of flattened fibroblasts Less amount of ground subsatnce Example Tendon Corena

Dense irregular connective tissue: 

Dense irregular connective tissue Dr Pankaj 42 Irregular bundles of collagen fibres cut at different planes Less cells and ground substance Example Dermis Capsule of many organ

Elastic connective tissue: 

Elastic connective tissue Dr Pankaj 43 Branching refractile bundles of elastic fibres Less cells and ground subsatnce between fibre bundles. Example Dermis Lung Elastic cartilage and ligaments Large blood vessel

Adipose tissue: 

Adipose tissue Special type of connective tissue formed by aggregation of fat cells. 15- 20 % of body weight in men and 20-25% in women. Derived from primitive mesenchyme where they develop as lipoblast . Found subcutaneously in hypodermis throughout the body except over eyelid, penis , scrotum and lobule of auricle 44 Dr Pankaj

Adipose tissue: 

Adipose tissue Function Reservoir of energy Shape to the body and keep organs in position Act as a shock absorber Thermal insulation to body 45 Dr Pankaj

Adipose tissue: 

Adipose tissue Dr Pankaj 46 Big rounded cell Single – unilocular Flat peripheral nucleus Few Low Well develop Less vascular Widespread – found in adults Store house of energy Small polygonal cell Many – multilocular Spherical central nucleus Many with long cristae High Not well developed Highly vascular Limited – foetues and new borns Production of heat White adipocytes Brown adipocytes

Adipose tissue: 

Adipose tissue Dr Pankaj 47 White adipocytes Brown adipocytes

Adipose tissue: 

Adipose tissue Dr Pankaj 48 Empty space in each fat cell giving a honey comb appearance (empty space is due to dissolution of lipid droplet) Thin rim of cytoplasm and eccentrically placed nuclei Lobules separated by septa

Applied anatomy: 

Applied anatomy Edema Hay fever and asthma Anaphylactic shock Obesity Hypertrophic obesity Hypercellular obesity Tumors Lipomas 49 Dr Pankaj

PowerPoint Presentation: 

50 Dr Pankaj

Ehlers Danlos Syndromes: 

51 Group of heritable connective tissue disorders Cutaneous findings – hyperextensible and fragile skin, poor wound healing, easy bruising, molluscoid pseudotumors Systemic features – joint hypermobility , scoliosis, significant risk of spontaneous arterial, intestinal or uterine rupture Ehlers Danlos Syndromes

Ehlers Danlos Syndromes: 

52 Ehlers Danlos Syndromes Genetic disorders ( Autosomal dominant) involving defect in the collagen. (Type III procollagen ) 12 variants of disease observed Type IV is greatest risk for aortic rupture because the normal aorta is rich in type III procollagen Characteristics: – Skin Hyperelasticity – Hypermobile joints

Marfan Syndrome: 

53 Marfan Syndrome Mutations in the fibrillin gene (FBN1) cause defective elastic fiber formation . Autosomal dominant disorder Lack of resistance in tissues rich in elastic fibers.

Marfan’s syndrome - Characteristics: 

54 Marfan’s syndrome - Characteristics Aortic aneurysm or dissection often occurring at the base of the aorta 2. Dislocation of lenses : Vision issues 3. Long thin extremities

Thank you……..: 

Thank you…….. Dr Pankaj 55