8 September 2006
Microanatomy Lab – Cartilage and Bone Lab
Dr. Robert Crissman, Ph.D.



Cartilage


  • Diagnostic Characteristics: Large round cells, avascular, perichondrium, lots of amorphous extracellular matrix
  • Active secretion of sulfated molecules so staining in extracellular matrix is darker
    • Aggrecan Aggregates made from keratin and chrondriotin
  • Two types of growth:
    • Interstitial Growth
      • Clumping chondroblasts in isogenous groups within the cartilage
      • May not see many fibers because cells are still growing
    • Appositional Growth
      • Two layers in perichondrium: fibrous layer and chondrogenic layer
        • Appositional growth of cartilage occurs in chondrogenic layer
  • No wandering or plasma cells

Elastic Tissue

  • Has perichondrium, avascular, large round cells, lots of extracellular matrix
  • Elastic fibers stain darkly, with fibers splitting in acute angles

Fibrocartilage

  • Two components of intervertebral disk:
    • Anulus fibrosis
      • Made of fibrocartilage – Collagen Type I
    • Nucleus pulposis – Gelatinous matrix
  • For shock absorption

Compact Bone


  • Dried specimen have osteocytes removed, leaving holes that have been filled with India ink.
    • Holes are the remaining lacunae
  • Canaliculi can be seen reaching towards the next cell
    • Inside are cellular processes of the osteocyte
  • Limits of individual osteons can be distinguished, and interstitial lamellae
    • Interstitial lamellae are remnants of former osteons and have incomplete parts of Haversian systems
    • Haversian canals are lined by bone lining cells
  • Volkmann’s canal appears like a dumbbell shaped structure without concentric rings of osteocytes
    • Volkmann’s canal runs perpendicularly to bone surface
    • Do not want Volkmann’s canal to run entire length of a bone because if the bone breaks, the indirect damage would kill all the cells in the bone when nutrient supplies are cut
  • Internal remodeling can be observed through osteoclast action
    • Resorbption canal can be found by looking for big holes the size of an osteon without concentric rings
    • Forming osteons look like a hole larger than central canal with a few concentric rings
  • Oldest osteocyte is nearest to the cement line