Cell Differentiation and Morphology
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Questions and Answers

What is the primary function of precursor cells in hematopoiesis?

  • To maintain the stem cell pool
  • To undergo apoptosis
  • To commit to forming a specific type of blood cell (correct)
  • To self-renew indefinitely

    • Which of the following is a characteristic of hematopoietic stem cells (HSCs)?

  • They are always committed to a specific lineage
  • They can give rise to various blood cell types (correct)
  • They are morphologically indistinguishable
  • They can only undergo apoptosis

    • In the stochastic model of hematopoiesis, what determines the fate of hematopoietic stem cells?

  • Intrinsic genetic programming
  • Pre-existing lineage specifications
  • Random commitment to self-renewal or differentiation (correct)
  • Environmental factors from the bone marrow

    • What role does the microenvironment in the bone marrow play according to the instructive model?

    <p>It dictates the specific lineage differentiation of HSCs</p> Signup and view all the answers

    Which stem cell markers are specifically associated with committed myeloid progenitors?

    <p>CD 33 and CD 38</p> Signup and view all the answers

    What is asymmetric division in the context of hematopoietic stem cells?

    <p>One daughter cell remains in the stem cell pool while the other differentiates</p> Signup and view all the answers

    Which lineage is NOT derived from the common myeloid progenitor?

    <p>T-lymphocyte lineage</p> Signup and view all the answers

    What is one possible outcome when hematopoietic stem cells undergo apoptosis?

    <p>The stem cell population decreases</p> Signup and view all the answers

    What morphological change occurs to the nucleus during cell differentiation?

    <p>Loss of nucleoli</p> Signup and view all the answers

    Which of the following is an intrinsic factor involved in hematopoiesis?

    <p>TAL1</p> Signup and view all the answers

    What effect do cytokines generally have on hematopoietic precursor cells?

    <p>They can regulate proliferation, differentiation, and maturation.</p> Signup and view all the answers

    Which of the following indicates a decrease during cell maturation?

    <p>N:C ratio</p> Signup and view all the answers

    Which cytokine is known to exert a stimulatory effect?

    <p>FLT3 ligand</p> Signup and view all the answers

    What happens to the size of the cytoplasm during differentiation?

    <p>It increases proportionally.</p> Signup and view all the answers

    Which of the following is an extrinsic factor in hematopoiesis?

    <p>Notch-1</p> Signup and view all the answers

    What role do cytokines play in apoptosis during hematopoiesis?

    <p>Inhibit apoptosis.</p> Signup and view all the answers

    Which factor stimulates the formation of colony-forming units for granulocyte and monocyte/macrophage?

    <p>M-CSF</p> Signup and view all the answers

    What is the primary role of interleukins in hematopoiesis?

    <p>Regulate the proliferation and differentiation of blood cells</p> Signup and view all the answers

    What happens to cells when they do not receive the appropriate cytokines?

    <p>Apoptosis is initiated</p> Signup and view all the answers

    Which cytokine is known to stimulate the formation of CFU-G, a colony-forming unit for granulocytes?

    <p>G-CSF</p> Signup and view all the answers

    What is the role of KIT Ligand in hematopoiesis?

    <p>Stimulate various cell lineages for differentiation</p> Signup and view all the answers

    Which characteristic is true about early-acting multilineage growth factors?

    <p>They provide a broad range of stimulation to hematopoietic cells</p> Signup and view all the answers

    What natural process is involved in eliminating unwanted or abnormal cells?

    <p>Apoptosis</p> Signup and view all the answers

    Which of the following statements about interleukins is true?

    <p>They have synergistic interactions with other cytokines.</p> Signup and view all the answers

    What type of cells does lymphopoiesis primarily produce?

    <p>Lymphocytes</p> Signup and view all the answers

    Which progenitor cell is responsible for generating mature T cells?

    <p>CFU-pre-T</p> Signup and view all the answers

    What is the final stage of cell development in megakaryopoiesis?

    <p>Platelets</p> Signup and view all the answers

    Which progenitor gives rise to both granulocytes and monocytes?

    <p>CFU-GM</p> Signup and view all the answers

    What is the role of CFU-pre-B in the hematopoietic process?

    <p>Development of mature B cells</p> Signup and view all the answers

    What is the primary biological activity of EPO?

    <p>Simulates proliferation of erythroid progenitors</p> Signup and view all the answers

    Which cell type does GM-CSF mainly target?

    <p>Dendritic cells</p> Signup and view all the answers

    IL-6 is associated with which of the following biological activities?

    <p>Stimulates megakaryocyte maturation</p> Signup and view all the answers

    The primary source of IL-10 is derived from which of the following cell types?

    <p>Macrophages</p> Signup and view all the answers

    IL-2 is essential for the activation of which cell types?

    <p>CD4+ T cells and CD8+ T cells</p> Signup and view all the answers

    Which factor primarily stimulates the maturation of neutrophils?

    <p>G-CSF</p> Signup and view all the answers

    IL-12 is known for promoting differentiation toward which type of T cells?

    <p>CD4+/CD8+ T cells</p> Signup and view all the answers

    The biological activity of IL-15 includes promoting which type of cell proliferation?

    <p>CD8+ T cells</p> Signup and view all the answers

    What is the primary role of IFN-α?

    <p>Enhances MHC expression</p> Signup and view all the answers

    Which of the following cytokines is known to inhibit cytokine production?

    <p>IL-10</p> Signup and view all the answers

    Study Notes

    Precursor Cells

    • Committed to forming specific types of blood cells.
    • Morphologically distinguishable and lineage-specific.

    Model of Hematopoiesis

    • Pluripotent Hematopoietic Stem Cells (HSCs) differentiate into two main progenitors:

      • Common Myeloid Progenitor → Granulocytic, Monocytic, Erythrocytic, and Megakaryocytic lineages.
      • Common Lymphoid Progenitor → T, B, NK-lymphocytes, and Dendritic lineages.

    • Stem Cell Markers:

      • CD 34 for Lymphoid & Myeloid precursors
      • CD 33 & CD 38 for Committed Myeloid Progenitors
      • CD 10 & CD 38 for Committed Lymphoid Progenitors
      • CD 7 for T-lymphoid Progenitor cells
      • CD 19 for B-lymphoid Progenitor cells

    Possible Fates of Hematopoietic Stem Cells

    • Self-renewal: HSCs replicate to maintain the stem cell pool.
    • Differentiation: HSCs divide either symmetrically (both daughters differentiate) or asymmetrically (one daughter remains an HSC and the other differentiates).
    • Apoptosis: HSCs die if they do not receive necessary signals.

    Theories on Stem Cell Fate

    • Stochastic Model: HSCs randomly choose between self-renewal or differentiation.
    • Instructive Model: Decisions influenced by the bone marrow microenvironment.
    • Current understanding suggests a combination of both models governs HSC fate.

    Morphologic Changes During Differentiation

    • Decrease in cell volume and alterations in nucleus-to-cytoplasm ratio (N:C).
    • Nucleus changes: Loss of nucleoli, reduced size, chromatin condensation, and alterations in shape.
    • Cytoplasm changes: Decreased basophilia and potential appearance of granules.

    Signals from the Hematopoietic Inductive Microenvironment

    • Intrinsic Factors: Gene expressions such as TAL1 and GATA2 regulate hematopoiesis.
    • Extrinsic Factors: Growth factors and cytokines modulate HSC behavior.
    • Regulatory Signaling Factors: Factors, including Notch-1 and Notch-2, enable HSC response to the microenvironment.

    Hematopoietic Growth Factors and Cytokines

    • Glycoproteins that regulate proliferation and differentiation of blood precursor cells.
    • Key types include interleukins, lymphokines, monokines, and colony-stimulating factors (CSFs).
    • Stimulatory cytokines: KIT ligand, FLT3 ligand, GM-CSF, IL-1, IL-3, IL-6, IL-11.
    • Inhibitory cytokines: Growth factor-β, TNF-α, and interferons.

    Roles of Cytokines

    • Prevent apoptosis, promote cell division, and regulate differentiation into cell lineages.
    • Apoptosis occurs when cells fail to receive necessary survival signals.

    Colony-Stimulating Factors (CSFs)

    • GM-CSF: Stimulates the formation of granulocyte and monocyte progenitors.
    • M-CSF: Promotes monocyte differentiation.
    • G-CSF: Encourages production of granulocyte colony-forming units.

    Early-acting Multilineage Growth Factors

    • KIT Ligand: Acts through KIT receptor; important for stem cell maintenance.
    • FLT3 Ligand: Functions via FLT3 receptor for HSC proliferation.

    Interleukins

    • Proteins that facilitate hematopoiesis with synergistic effects with other cytokines; active at low concentrations.

    Selected Hematopoietic Growth Factors or Cytokines

    • EPO: Produced by kidney; stimulates erythroid progenitor growth and survival.
    • G-CSF: Originates from endothelial cells; promotes neutrophil progenitor colonies.
    • GM-CSF: Involved in T cell activation and antigen presentation.

    Lymphopoiesis

    • The production process of lymphocytes from Pluripotent HSCs.

    Megakaryopoiesis

    • The production pathway of platelets from HSCs through multiple progenitor stages.

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    Description

    This quiz explores the morphologic changes that occur during cell differentiation and maturation. Key topics include changes in cell volume, nucleus structure, and nucleus to cytoplasm ratio. Test your understanding of these essential biological processes.

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