Lineage Specific Hematopoiesis

• What are the main topics covered in the Red Cell Maturation Series?

  • Maturation Process
  • Criteria Used in Identification of Erythroid Precursors
  • Maturation Sequence
• What is the primary function of red blood cells (erythrocytes)?

  To carry oxygen from the lungs to the tissues
• How does oxygen attach to red blood cells?

  Oxygen attaches to hemoglobin, the major cytoplasmic component of mature RBCs
• What are erythroblasts?

  Nucleated RBC precursors, normally restricted to the bone marrow
• What are the three nomenclatures for erythroid precursors?

  • Normoblastic
  • Rubriblast
  • Erythroblast
• What does the term "normoblastic" refer to?

  It is commonly used in the United States and describes the appearance of the cells
• What is the significance of the Burst-Forming Unit Erythroid (BFU-E)?

  It gives rise to large colonies capable of multi-subunit colonies (bursts)
• How long does it take for BFU-E to mature to CFU-E?

  1 week
• What is the maturation time required to produce a mature RBC from BFU-E?

  Approximately 18 to 21 days
• What is the role of the Romanowsky stain in identifying erythroid precursors?

  It is used to examine the stage of maturation of blood cells
• What are the key features in the identification of RBCs?

  • Nuclear chromatin pattern
  • Nuclear diameter
  • Nucleus to cytoplasm (N:C) ratio
  • Presence or absence of nucleoli
  • Cytoplasmic color
• What general trend affects the appearance of erythroid precursors during maturation?

  The overall diameter of the cell decreases
• What happens to the nuclear chromatin pattern as erythroid precursors mature?

  It becomes coarser, clumped, and condensed
• What is the main regulator of erythropoiesis?

  Erythropoietin (EPO) from the kidneys
• What is the N:C ratio of a pronormoblast?

  1. 1
• What is the primary cellular activity of a pronormoblast?

  To begin accumulating components necessary for hemoglobin production
• How long does a pronormoblast typically remain in its stage?

  Slightly more than 24 hours
• What happens to the nucleus of an orthchromic normoblast during maturation?

  The nucleus is ejected from the cell
• What is the predominant color of the cytoplasm in a polychromatic erythrocyte?

  Salmon pink
• How long does a polychromatic erythrocyte reside in the bone marrow before moving to peripheral blood?

  About 1 to 2 days
• What are the stages of red cell maturation in order?

  1. Pronormoblast
  2. Basophilic Normoblast (Prorubricyte)
  3. Polychromatic Normoblast
  4. Orthochromic Normoblast
  5. Polychromatic Erythrocyte (Reticulocyte)
  6. Erythrocyte
• What are the key characteristics of the basophilic normoblast?

  • Nucleus: Chromatin begins to condense, N:C ratio ~6:1
  • Cytoplasm: Deeper blue color
  • Division: Undergoes mitosis
  • Location: Present in bone marrow
  • Cellular Activity: Detectable hemoglobin synthesis
• What are the key characteristics of the polychromatic normoblast?

  • Nucleus: Condensed chromatin, N:C ratio decreases from 4:1 to 1:1
  • Cytoplasm: First stage showing pink color from hemoglobin
  • Division: Last stage capable of mitosis
  • Location: Present only in bone marrow
  • Cellular Activity: Increased hemoglobin synthesis
• What are the key characteristics of the orthchromic normoblast?

  • Nucleus: Completely condensed, N:C ratio ~1:2
  • Cytoplasm: Salmon pink color due to hemoglobin production
  • Division: Not capable of division
  • Location: Bone marrow
  • Cellular Activity: Hemoglobin production continues
• What are the key characteristics of the polychromatic erythrocyte?

  • Nucleus: No nucleus
  • Cytoplasm: Predominantly hemoglobin with bluish tinge
  • Division: Cannot divide
  • Location: Resides in bone marrow for 1-2 days, then moves to peripheral blood
  • Cellular Activity: Completes hemoglobin production
• What is the significance of the maturation sequence in erythropoiesis?

  It regulates the process for maintaining adequate numbers of red blood cells in the peripheral blood
• What is the role of splenic macrophages in the maturation of erythrocytes?

  They assist in pitting inclusions and membrane polishing
• What is the final stage of red blood cell maturation?

  Erythrocyte
• What is the primary function of thrombocytopoiesis?

  To shed platelets from megakaryocytes
• What are the stages of white cell maturation series?

  • Granulocyte
  • Neutrophils
  • Eosinophils
  • Basophils
  • Mast Cells
  • Mononuclear Cells
  • Monocytes
  • Lymphocytes
• What are the key characteristics of megakaryopoiesis?

  • Megakaryocyte differentiation and progenitors
  • Thrombocytopoiesis (platelet shedding)
• What are the functions of monocytes/macrophages?

  • Phagocytosis of pathogens
  • Antigen presentation
  • Cytokine production
• What are the functions of lymphocytes?

  • B cells: Antibody production
  • T cells: Cell-mediated immunity
  • Natural killer cells: Targeting infected or cancerous cells
• What are the functions of eosinophils?

  • Combat parasitic infections
  • Involved in allergic reactions
  • Modulate inflammatory responses
• What are the functions of basophils?

  • Release histamine during allergic reactions
  • Involved in inflammatory responses
  • Play a role in immune response
• What are the functions of neutrophils?

  • First responders to infection
  • Phagocytosis of pathogens
  • Release of enzymes and antimicrobial substances
• What color is a mature red blood cell (RBC)?

  Salmon pink
• Why can't the polychromatic erythrocyte divide?

  Because it lacks a nucleus
• How long does the polychromatic erythrocyte reside in the bone marrow?

  About 1 to 2 days
• What happens to the polychromatic erythrocyte after it leaves the bone marrow?

  It moves into the peripheral blood for about 1 day before reaching maturity