Blood

• Bone Marrow


  • Red
  • Reticular connective tissue (stroma)
  • Hemopoietic cords
  • Sinusoidal capillaries
  • Stromal cells
• Stromal cells

  • Reticular or adventitial
  • Supports the bone marrow
  • Fibroblastic cells
  • Support hemopoietic cells and macrophages
• Hemopoiesis

  1. Early development - RBC production at the mesoderm (yolk sac)

  2. 2nd trimester - Liver and spleen: minor role in RBC production

  3. 3rd trimester - Bone marrow develops and becomes major hematopoietic organ

  4. 6 months to after birth: continuous development
• Major progenitor cells

  • Erythroid lineage
  • Thrombocytic lineage
  • Granulocytic lineage
  • Monocytic lineage
  • Lymphoid lineage
• Growth factors and hormones

  • G-CSF: neutrophil
  • GM-CSF: basophil, eosinophil
  • M-CSF: monocyte
  • Erythropoietin (kidney)
  • Thrombopoietin (liver)
• Blood smear staining


  • Romanowsky: blood films
  • Giemsa: Giemsa powder + glycerol + methyl alcohol
  • Wright: dip in undiluted smear for 30 secs to 1 min
• Red blood cells (RBCs)

  • Anuclear, biconcave
  • Carry O2 and CO2
  • Unstained: pale yellow
  • Stained: salmon pink
  • 120 days lifespan
  • Male: 4.1-6 million/ uL
  • Female: 3.9-5.5 million/uL
• Neutrophils


  • Polymorphonuclear leukocyte
  • 50-70%
  • 1-4 days in tissue
  • 8 hrs in blood
  • 2-5 lobes
  • 1st to respond to bacteria
• Eosinophils


  • Parasitic infection
  • 2-5%
  • 8-12 days in tissue
  • 3-8 hrs in blood
  • Bilobed
  • Arginine rich factors that account granules
• Basophils


  • Allergy
  • 0-1%
  • Few days
  • Histamine
  • Receptors for IgE
• Monocytes


  • Inflammation
  • Mononucleosis
  • C-shaped
  • 3-7%
  • 1-2 days
• Lymphocytes


  • Viral infection
  • Spherical nuclei
  • 20-40%
  • T lymphocyte: several months
  • B lymphocyte: several years
• Thrombocytes


  • Blood clot
  • 9-12 days
  • 150 000 – 450 000/ cu mm
  • Read using OIO