Connective tissue/bone & cartilage lec

• Connective Tissue Cells


  Fixed Cells and Free Cells
• Fixed Cells


  • Fibroblasts

  2. Mesenchymal cells

  3. Reticular cells

  4. Fat cells
• Free Cells


  • - WBC
  • Mast cells
  • Plasma cells
  • Macrophages
• Ground Matrix


  Amorphous Ground Substance - Acid mucopolysaccharide or glycosaminoglycans (GAGs) such as Hyaluronic acid, Chondroitin sulfate, Dermatan sulfate, Keratan sulfate, Heparan sulfate
• Connective Tissue Fibers


  • Collagen Fibers

  2. Elastic Fibers

  3. Reticular Fibers
• Collagen Fibers


  • - Most abundant fibers
  • 2-10 um in diameter
  • Have a tensile strength greater than steel
  • Flexible but inelastic
  • Acidophilic
  • Colorless to white in fresh tissue
  • Masson's trichome technique - blue
  • Fibroblast synthesis: Procollagen -> Tropocollagen -> Microfibrils -> Macrofibrils -> Collagen fibers
• Elastic Fibers


  • - 1 um in diameter
  • Yellow color in fresh tissue
  • Made up of Elastin
  • H&E, refractile, pinkish-yellow lines
  • Orcein stain, blue to black
  • Lesser tensile strength
  • Highly insoluble protein
  • Exist in 2 forms: Fibrillar form and Non-fibrillar form
  • Found in Ligamenta Flava between vertebrae, Extracellular spaces of the elastic cartilages that form the framework of the Auricle, External acoustic meatus of the ear, External nose, Auditory tube, Epiglottis, Some parts of the larynx
• Reticular Fibers


  • - 0.5-2 um in diameter
  • Type III collagen
  • Tend to form network
  • Argyrophilic fibers
  • Found in Basal lamina of most epithelia, Bone marrow, Liver, Lymph nodes, Spleen
• General Classes of Connective Tissue

  • - Loose Connective Tissue
  • Ordinary Loose Connective Tissue
  • Modified Loose Connective Tissue
  • Dense Connective Tissue
  • Dense Regular Connective Tissue
  • Dense Irregular Connective Tissue
  • Adipose Tissue
  • Mucous Tissue
• Modified Loose Connective Tissue

  • - Elastic fiber is the predominant fibrillar component
  • Form bundles with few collagenous fibers and fibroblasts
  • Found in the wall of hollow organs, Large artery (tunica media of aorta), Internal elastic membrane of medium sized artery, Trachea, Bronchi, Vocal cords, Ligamentum flava of vertebral column, Suspensory ligament of the penis
• Dense Regular Connective Tissue

  • - Fibers are arranged in a definite pattern
  • Found in Tendons, Ligaments, Fibrous membranes, Sheath of large nerves, Periosteum,
• Dense Irregular Connective Tissue

  • - Collagen fibers run in various directions
  • Found in Dermis of the skin, Capsule of some organs, Lymph nodes, Liver, Spleen, Testis
• Adipose Tissue


  • Functions:
  • Storage of fat
  • Thermal insulator
  • Mechanical support in certain body regions

  Types:

  • Yellow or White Adipose Tissue (Adult fat/Mature fat - store lipid in single fat vacuole, found in subcutaneous tissue, omentum, mesenteries, retroperitoneal fat)
  • Brown or Multilocular Adipose Tissue (Fetal fat/Immature form - store lipid in numerous droplets, found in interscapular and inguinal regions of newborn)
• Mucous Tissue


  • - Amorphous ground substance - hyaluronic acid
  • Few cellular elements - fibroblasts, occasional macrophages
  • Found in Wharton's Jelly of umbilical cord, Pulp of young teeth
• Bone: Functions


  • Provides solid support for the body
  • Protects vital organs
  • Reservoir of calcium, phosphate and other ions
  • Confers mechanical and metabolic functions to the skeleton
• Bone Cell Types


  • OSTEOBLASTS
  • OSTEOCYTES
  • OSTEOCLASTS
• Osteoblasts


  • Bone-forming cells
  • Bone Matrix
  • Type I Collagen Fibers
  • Proteoglycans
  • Osteonectin
  • Surface of Bone Matrix
  • Large, cuboidal cells
  • Basophilic
• Osteocytes


  • Mature cells
  • Occupies the LACUNA
  • Stellate-shaped
  • Mononucleated
• Osteoclasts


  • LARGE, MOTILE, MULTINUCLEATED GIANT CELLS
  • EOSINOPHILIC
  • LOCATED IN THE LINING OF ENDOSTEUM, IN A DEPRESSION KNOWN AS HOWSHIP LACUNAE OR RESORPTION LACUNAE
  • INVOLVE IN RESORPTION AND REMODELING
• Bone Matrix


  • ORGANIC
  • INORGANIC
• Organic Bone Matrix


  • Type I collagen (90%)
  • Small Proteoglycans
  • Multiadhesive Glycoproteins
  • Osteonectin
  • Calcium-Binding Proteins
  • Osteocalcin
  • Phosphatases
• Inorganic Bone Matrix


  • Calcium Hydroxyapatite
  • HCO3
  • Citrate
  • Magnesium
  • Potassium
  • Sodium
• Periosteum


  • THIN LAYER OF SQUAMOUS CELLS
  • CONTENTS:
  • OSTEOPROGENITOR CELLS
  • OSTEOBLASTS
  • BONE LINING CELLS
• Endosteum


  THIN LAYER OF SQUAMOUS CELLS
• Types of Bone


  • COMPACT BONE
  • CANCELLOUS BONE
• Osteogenesis


  1. INTRAMEMBRANOUS OSSIFICATION

  2. ENDOCHONDRIAL OSSIFICATION
• Cartilage


  • Consists of:
  • Cells – CHONDROCYTES
  • Extracellular matrix:
  • Fibers
  • Ground substance
  • hyaluronic acid
  • proteoglycans
  • glycoproteins
• Chondrocytes


  • Flattened to oval to spherical
  • Lodged in lacuna
  • In singly or isogenous group
  • Nucleus: round or oval, pale staining, with nucleoli
  • Cytoplasm: basophilic,with mitochondria, occ lipid droplets, glycogens
• Hyaline Cartilage


  • Most common form
  • Homogenous and semitransparent
  • Found in:
  • Epiphyseal disc
  • Ventral & costal cartilage of rib
  • Cricoid and thyroid cartilage of the larynx
  • Cartilagenous rings of trachea & bronchi
  • Articular cartilage
• Elastic Cartilage


  • More flexible type
  • Found in:
  • Auricle
  • Walls of the external auditory canal
  • Eustachian tube
  • Epiglottis
  • Epiglottic cartilage of larynx
• Fibrous Cartilage


  • Characteristic between dense c.t. and hyaline cartilage
  • Found in the:
  • Symphysis pubis
  • Intervertebral disc