blood lab

• Blood and bone marrow

  The different stages of formed elements of the blood (RBC, WBC, platelets) are shown in the bone marrow
• Stages of formed elements of the blood

  • Red blood cells
  • White blood cells
  • Platelets
• Red blood cells

  • Non-nucleated
  • Biconcave disc
  • Average diameter is 7.5 um
  • Transports oxygen from the lungs to the tissues and carbon dioxide from the tissues to the lungs
• White blood cells

  • Polymorphonuclear
  • Normal value: 55-65%
  • Increased in bacterial infection
• Eosinophil

  • Bilobed nucleus
  • Eosinophilic cytoplasm
  • Increased in helminthic and parasitic infections
  • Increased in allergic reactions
• Basophil


  • Large bilobed nucleus
• Lymphocyte


  • Characterized by large nucleus that occupies most of its cytoplasm
  • Increased in viral infection
• Monocyte

  • "kidney-shaped" or "bean-shaped"
  • Largest of the formed elements
  • Cytoplasm is more abundant and has a grayish blue tint
  • They stay in the circulation for an average of 72 hours before they are deposited in the tissues and are converted to macrophage
• Platelets

  • Biconcave discs
  • 2 to 3 um in diameter
  • Non-nucleated
  • Clusters or groups
  • NV: 150,000 to 300,000/ mm3
  • Fragmentation of the cytoplasm of megakaryocytes leads to the formation of platelets