Cell Differentiation and Morphology

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?

It dictates the specific lineage differentiation of HSCs Signup and view all the answers

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

CD 33 and CD 38 Signup and view all the answers

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

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

Which lineage is NOT derived from the common myeloid progenitor?

T-lymphocyte lineage Signup and view all the answers

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

The stem cell population decreases Signup and view all the answers

What morphological change occurs to the nucleus during cell differentiation?

Loss of nucleoli Signup and view all the answers

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

TAL1 Signup and view all the answers

What effect do cytokines generally have on hematopoietic precursor cells?

They can regulate proliferation, differentiation, and maturation. Signup and view all the answers

Which of the following indicates a decrease during cell maturation?

N:C ratio Signup and view all the answers

Which cytokine is known to exert a stimulatory effect?

FLT3 ligand Signup and view all the answers

What happens to the size of the cytoplasm during differentiation?

It increases proportionally. Signup and view all the answers

Which of the following is an extrinsic factor in hematopoiesis?

Notch-1 Signup and view all the answers

What role do cytokines play in apoptosis during hematopoiesis?

Inhibit apoptosis. Signup and view all the answers

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

M-CSF Signup and view all the answers

What is the primary role of interleukins in hematopoiesis?

Regulate the proliferation and differentiation of blood cells Signup and view all the answers

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

Apoptosis is initiated Signup and view all the answers

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

G-CSF Signup and view all the answers

What is the role of KIT Ligand in hematopoiesis?

Stimulate various cell lineages for differentiation Signup and view all the answers

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

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

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

Apoptosis Signup and view all the answers

Which of the following statements about interleukins is true?

They have synergistic interactions with other cytokines. Signup and view all the answers

What type of cells does lymphopoiesis primarily produce?

Lymphocytes Signup and view all the answers

Which progenitor cell is responsible for generating mature T cells?

CFU-pre-T Signup and view all the answers

What is the final stage of cell development in megakaryopoiesis?

Platelets Signup and view all the answers

Which progenitor gives rise to both granulocytes and monocytes?

CFU-GM Signup and view all the answers

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

Development of mature B cells Signup and view all the answers

What is the primary biological activity of EPO?

Simulates proliferation of erythroid progenitors Signup and view all the answers

Which cell type does GM-CSF mainly target?

Dendritic cells Signup and view all the answers

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

Stimulates megakaryocyte maturation Signup and view all the answers

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

Macrophages Signup and view all the answers

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

CD4+ T cells and CD8+ T cells Signup and view all the answers

Which factor primarily stimulates the maturation of neutrophils?

G-CSF Signup and view all the answers

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

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

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

CD8+ T cells Signup and view all the answers

What is the primary role of IFN-α?

Enhances MHC expression Signup and view all the answers

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

IL-10 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.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

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.