20.11.2014
CONNECTIVE TISSUE
Dr. Archana Rani Associate Professor Department of Anatomy KGMU UP, Lucknow
CONNECTIVE TISSUE
INTRODUCTION
Connective tissue serve as a connecting link for binding, supporting and strengthening all other body tissues together.
CONNECTIVE TISSUE
• GENERAL FEATURES
1. Cells 2. Matrix -Fibres -Ground substance CONNECTIVE TISSUE
• Cells
• Fibres
• Ground substance
Cells of Connective Tissue
A. Fixed cells (intrinsic cells) 1. Fibroblast 2. Mesenchymal cells 3. Adipocyte Mast cell Mesenchymal cell 4. Pigment cells B. Free cells (extrinsic cells) 5.Macrophage (histiocyte) Fibroblast 6. Mast cell 7. Plasma cells 8. Leucocytes
Plasma cell Adipocyte
Fibroblast • Most commonly seen ( in all types of connective tissue) • Fusiform with slender cytoplasmic process • Large oval nucleus • Responsible for fiber production • Old (inactive) cells are fibrocytes • Contractile cells are myofibroblasts • More at sites of wound healing Fibroblast Adipocytes (Fat cells)
• Signet-ring like appearance • Store lipid • Appears as empty space • Do not undergo cell division • May occur singly as in loose areolar tissue • May occur in groups as in adipose tissue Mesenchymal cells
• Undifferentiated cells • Stellate in shape • Cytoplasmic process • Pluripotent cell • Along blood vessels Macrophages (Histiocytes) • Free and Fixed type Fixed Cells (histiocytes)- • Irregular Shape • Short branching processes • Dark indented eccentric nucleus, • Derived from monocyte • Involved in phagocytosis • Fused to form giant cell. Free Cells- rounded, absence of processes Plasma cells
• Oval basophilic cells • Eccentric nucleus • Heterochromatin as cartwheel nucleus • Derived from B lymphocyte • Produces immunoglobulin • Antibody collected as Russell body • Present in respiratory tract and gastrointestinal tract Mast cells
• Round or fusiform shaped
• Packed with coarse granules
• Present in serous membranes
• Mostly along blood vessels
• Show Metachromasia
• Granules have histamine and heparin
Leucocytes
. Granulocytes- Neutrophils Eosinophils Basophils . Agranulocytes- Neutrophil Eosinophil Lymphocytes Monocytes
Lymphocyte Basophil
Monocyte Leucocytes Collagen Fibres
• White coloured when fresh • Do not branch • Found in abundance in bone, cartilage, tendon & ligament • Strong, flexible & inelastic • Present in bundle • Collagen protein form fibres • Fibres are composed of fibril formed by microfibrilar subunits • Micro fibrils are made up of tropocollagen • Synthesized by fibroblast Types of Collagen fibre
• Type 2-cartilage (hyaline & elastic)
• Type 3-reticular fibres
• Type 4-basement membrane
• Type 5-blood vessels Synthesis of Collagen fibre Amino acids
Procollagen
Three chains
Tropocollagen
Collagen
Elastic fibres • Very thin but strong • Composed of elastin protein • Branch and anastomose freely • Can be stretched • Run singly & branch forming network in loose areolar tissue • In bundles, found in ligamentum flava & ligamentum nuchae • Synthesized by fibroblast • Found in skin, ligamentum flava & nuchae and large arteries
Reticular fibres
• Fine delicate strands • Immature collagen fibre (type -3) • Synthesized by fibroblasts • Provide support and strength • Framework of lymphoid tissue • In organ capsules of liver, kidney & endocrine glands • Stained by silver salts (argyrophilic) Ground substance • Mixture of glycoproteins & proteoglcans
• Proteoglycans (glycosaminoglycans)- hyaluronic acid, chondroitin sulphate, heparan sulphate, keratan sulphate, dermatan sulphate
• Glycoprotiens- fibronectin (dermis), chondronectin (cartilage), laminin (basement membrane)
• Colourless
• Highly hydrated
• Provides medium through which substances are exchanged between blood and cells
Classification of Connective tissue
1. Embryonic connective tissue: Mucus (umbilical cord) Mesenchymal (developing embryo & fetus)
2. Connective tissue proper: Loose connective tissue (Areolar tissue) Adipose tissue Reticular tissue Dense connective tissue
Classification (contd…..)
Dense connective tissue: Irregular dense connective tissue Regular dense connective tissue Elastic connective tissue
3. Specialized connective tissue: Bone Cartilage Blood
Loose connective tissue Loose connective tissue Dense irregular connective tissue
Dense regular connective tissue Dense regular connective tissue
Adipose tissue
References
1. diFiore’s Atlas of Histology with functional Correlations, 12th Edition.
2. Essentials of Anatomy for Dentistry Students,1st Edition.
3. Textbook of Histology, 3rd Edition.
MCQ
• Most common type of connective tissue cell is: 1. Mast cell 2. Plasma cell 3. Fibroblast 4. Mesenchymal cell
MCQ
• Cartwheel appearance of nucleus is a feature of: 1. Macrophage 2. Mast cell 3. Plasma cell 4. Pigment cell
MCQ
• Metachromasia is a feature of: 1. Mast cells 2. Adipocytes 3. Macrophages 4. Mesenchymal cells
MCQ
• The important feature of collagen fibre is: 1. Branched 2. Elastic 3. Anastomose freely 4. Present in bundles MCQ
• The framework of spleen is made up of: 1. Plasma cells 2. Mesenchymal cells 3. Elastic fibres 4. Reticular fibres