Connective Tissue

• Describe the general classification of connective tissue
  • Embryonic Connective Tissue
    • Mesenchyme
    • Mucous Connective Tissue (Wharton’s Jelly)
  • Connective Tissue Proper
    • Loose Connective Tissue
    • Dense Connective Tissue
      • Regular
      • Irregular
  • Specialized Connective Tissue
    • Cartilage
    • Bone
    • Adipose Tissue
    • Blood
    • Haematopoietic Tissue
    • Lymphatic Tissue

Distinguish between resident and non-resident connective tissue cells and give examples in each class

• List down at least 5 connective tissue resident cells
  • Fibroblasts
  • Myofibroblasts
  • Macrophages
  • Adipocytes
  • Mast cells
  • Adult stem cells
• List down at least 5 connective tissue non-resident cells ***Basically white blood cells
  • Lymphocytes
  • Plasma cells
  • Neutrophils
  • Eosinophils
  • Basophils
  • Monocytes
• Briefly describe the stages of collagen synthesis
  • Intracellular events
    • Collagen a-chains are synthesized in the Rough Endoplasmic Reticulum (RER) as long precursors containing large globular amino and carboxy terminus propeptides called pro-a-chains (preprocollagen)
    • Pre-procollagen undergoes post-translational modification in the cisternae of the RER to form procollagen molecules. These modifications include:
      • Cleavage of the amino-terminus signal
      • Hydroxylation of proline and lysine residues (Requires Vitamin C)
      • O-linked glycosylation of hydroxylysine residues and N-linked glycosylation at the two terminal positions
      • Formation of a triple helix consisting of 3 a-chains
      • Intrachain and interchain hydrogen and disulfide bonds are added to the triple helix
      • Heat shock proteins stabilize the triple helix and prevent their premature aggregation in the cells
    • Procollagen molecules pass to the Golgi apparatus where there are packed into secretory vesicles and transported to the cell surface
  • Extracellular events
    • Procollagen is converted into Mature collagen molecules by procollagen peptidases. They cleave the uncoiled ends of the procollagen molecules
    • Aggregated collagen molecules align together to form collagen fibrils in a process known as fibrillogenesis. They are cross-linked by covalent bonds between lysine and hydroxylysine aldehyde groups.
• State the connective tissue fiber affected in the following diseases: Osteogenesis imperfecta, Ehlers Danlos Type 4, Achondrogenesis, Marfan syndrome
  • Osteogenesis imperfecta: Type I collagen
  • Ehlers-Danlos type 4 syndrome: Type III collagen
  • Achondrogenesis: Type II collagen
  • Marfan Syndrome: Elastin fibers
• List examples of cells of mononuclear phagocytic system and state their respective locations
  • Monocytes: Blood and Bone marrow
  • Macrophage: Connective tissue, spleen, lymph nodes, Bone marrow, thymus
  • Kupffer histiocytes: Liver
  • Alveolar macrophages: Lungs
  • Hofbauer cell: Placenta
  • Pleural and peritoneal macrophages: Serous cavities
  • Osteoclast: Bone
  • Microglia: CNS
  • Langerhans cell: Epidermis of skin, oral mucosa, foreskin, female genital epithelium
  • Fibroblast-derived macrophage: Lamina propria of intestine, endometrium of uterus
  • Dendritic cell: Lymph nodes, spleen
  • Multinucleated giant cells (Foreign body giant cells, Langhans giant cell): Fused macrophages in Granulomas

As regards leukocytes, distinguish between granulocytes and agranulocytes

• State the predominant connective tissue fibers of the following: Hyaline cartilage, Elastic cartilage, Fibrocartilage
  • Hyaline cartilage: Type II collagen
  • Elastic cartilage: Elastic fibers and Type II collagen
  • Fibrocartilage: Type I collagen and Type II collagen
• Name 2 sites that contain elastic cartilage
  • External ear
  • The walls of the external acoustic meatus
  • The Eustachian tube
  • The epiglottis
• Name 2 major components of the extracellular matrix and their subclassification
  • Fibers: Collagen, Elastic fibers
  • Ground substance: Proteoglycans, Multiadhesive glycoproteins, glycosaminoglycans