DEVELOPMENT OF CONNECTIVE TISSUE Mesenchyme Loose Connective Tissue

DEVELOPMENT OF CONNECTIVE TISSUE Mesenchyme Loose Connective Tissue Fibers Fibroblasts Mesenchymal Cells

Cell Lineage from Mesenchymal Cells

TYPES OF CONNECTIVE TISSUE Loose Connective Tissue (e. i. mesentery, omentum) Dense Irregular Connective Tissue (e. i. dermis of skin) Dense Regular Connective Tissue (e. i. tendons, ligaments, cornea)

DENSE IRREGULAR CONNECTIVE TISSUE (DERMIS OF SKIN)

DENSE REGULAR CONNECTIVE TISSUE Tendon (longitudinal Section) Tendon (tranverse Section)

ELASTIC CONNECTIVE TISSUE IN BLOOD VESSEL WALL Internal elastic lamina

CONNECTIVE TISSUE FIBERS Collagenous Fibers (bundles) Reticular Fibers (networks) Elastic Fibers (anastomosing bundles)

RETICULAR CONNECTIVE TISSUE reticular fibers (argyrophilic)

COLLAGEN Fiber Fibril Microfibril FIBER BUNDLE Periodic Bands Tropocollagen alpha 1 peptide alpha 2 peptide TEM of Collagen Fibers SEM of Collagen Fibers

SCANNING EM OF COLLAGEN FIBER BUNDLES

TEM of Fibroblast and Collagen Bundles FIBROBLAST collagen fiber bundles RER procollagen tropocollagen ground substance (mucopolysaccharide) Collagen Types I - skin, bone, tendon cornea (most common type) II- cartilage, embryonic cornea III- reticular fibers, loose c. t. , blood vessel walls, dermis IV- basal lamina of epithelium (no fibers, mat of randomly-oriented molecules)

TEM OF FIBROBLAST WITH COLLAGEN BUNDLES

FIXED CONNECTIVE TISSUE CELL TYPES Fibroblast (fiber producing cell) Fibrocyte (mesenchymal- pluropotent) Adipocytes (fat storage) Fixed Macrophage (histiocyte)

Fixed Connective Tissue Cells Macrophage (light micrograph) Adipocytes fibroblast TEM of Macrophage

MONONUCLEAR PHAGOCYTIC SYSTEM (reticuloendothelial system) Giant Cell Monocyte Mononuclear wandering cell Macrophages spleen lymph nodes bone marrow connective tissue lung serous cavities coalescence Osteoclasts Kupffer Cells bone resorption liver sinusoids Microglial Cells Sinusoidal Endothelia central nervous system liver spleen marrow ( all characterized by phagocytic activity)

LYMPHOCYTES AND PLASMA CELLS (Agents of the immune response) Lymphocytes Plasma Cells differentiation stimulated by immune activation (produce immunoglobulins -antibodies)

EOSINOPHILES actively phagocytic destroy immune complexes (antigen-antibody) MAST CELLS Secretion Products: 1. Slow-reaction substance of anaphalaxis 2. Heparin- anticoagulant 3. Histamine- stimulates inflammation 4. Serotonin- vasoconstrictor 5. Eosinophil Chemotactic Factor

Connective Tissue Cells Plasma Cell Lymphocyte Macrophage

TRANSMISSION EM OF AN EOSINOPHILE

TRANSMISSION EM OF A MAST CELL