Podcast
Questions and Answers
What is the role of thrombopoietin-producing osteoblasts in the maintenance of HSCs?
What is the role of thrombopoietin-producing osteoblasts in the maintenance of HSCs?
- They inhibit cell-cell interactions in the bone marrow cavity.
- They regulate migration of HSCs to the vascular niche.
- They maintain HSCs in a quiescent state. (correct)
- They induce HSCs to proliferate.
What is the function of CXCL12 in the bone marrow niche?
What is the function of CXCL12 in the bone marrow niche?
- It regulates the migration of HSCs to the vascular niche. (correct)
- It inhibits the migration of HSCs to the vascular niche.
- It regulates cell-cell interactions between HSCs and osteoblasts.
- It induces HSCs to proliferate.
What is the significance of the heterogeneous microenvironment in the bone marrow niche?
What is the significance of the heterogeneous microenvironment in the bone marrow niche?
- It ensures uniform signaling to HSCs.
- It inhibits cell-cell interactions in the bone marrow cavity.
- It allows for the migration of HSCs to the peripheral circulation.
- It affects HSCs differently depending on location and cell type encountered. (correct)
What is the role of endothelial cells in the bone marrow niche?
What is the role of endothelial cells in the bone marrow niche?
What is the significance of understanding cell-cell interactions in the bone marrow niche?
What is the significance of understanding cell-cell interactions in the bone marrow niche?
What is the likely outcome of the overlap of niches in the bone marrow cavity?
What is the likely outcome of the overlap of niches in the bone marrow cavity?
During which phase of fetal development does hematopoiesis in the aorta-gonad-mesonephros region disappear?
During which phase of fetal development does hematopoiesis in the aorta-gonad-mesonephros region disappear?
What is the primary site of hematopoiesis during the second trimester of fetal life?
What is the primary site of hematopoiesis during the second trimester of fetal life?
At what stage of fetal development does the production of megakaryocytes begin?
At what stage of fetal development does the production of megakaryocytes begin?
During which phase of fetal development does the spleen contribute solely to lymphopoiesis?
During which phase of fetal development does the spleen contribute solely to lymphopoiesis?
What is the first fully developed organ in the fetus that becomes the major site of T cell production?
What is the first fully developed organ in the fetus that becomes the major site of T cell production?
During which phase of fetal development does hematopoiesis in the bone marrow reach its peak?
During which phase of fetal development does hematopoiesis in the bone marrow reach its peak?
What is the primary site of hematopoiesis in healthy adults?
What is the primary site of hematopoiesis in healthy adults?
When does hematopoiesis in the fetal liver reach its peak?
When does hematopoiesis in the fetal liver reach its peak?
What is the result of nondevelopment of the thymus during gestation?
What is the result of nondevelopment of the thymus during gestation?
What is the term for the ability of HSCs to give rise to all blood cell lineages?
What is the term for the ability of HSCs to give rise to all blood cell lineages?
What is the most widely accepted theory among experimental hematologists regarding the origin of blood cell lineages?
What is the most widely accepted theory among experimental hematologists regarding the origin of blood cell lineages?
What is the term for the single progenitor stem cell that gives rise to all blood cell lineages?
What is the term for the single progenitor stem cell that gives rise to all blood cell lineages?
Why are adults with thymic disturbance not affected?
Why are adults with thymic disturbance not affected?
What is the term for the ability of HSCs to divide and give rise to more HSCs?
What is the term for the ability of HSCs to divide and give rise to more HSCs?
What is the consequence of lack of formation of T lymphocytes in infants?
What is the consequence of lack of formation of T lymphocytes in infants?
What is the characteristic of HSCs that allows them to give rise to multiple cell types?
What is the characteristic of HSCs that allows them to give rise to multiple cell types?
What is the primary function of chemokines in the immune system?
What is the primary function of chemokines in the immune system?
What is the term used to describe the release of HSCs from the bone marrow compartment into the peripheral circulation?
What is the term used to describe the release of HSCs from the bone marrow compartment into the peripheral circulation?
What is the purpose of targeting the HSC-microenvironment niche interaction in transplantation-based HSC collection?
What is the purpose of targeting the HSC-microenvironment niche interaction in transplantation-based HSC collection?
What is the name of the proteins that are mentioned as complementing cytokine function and helping to regulate the adaptive and innate immune system?
What is the name of the proteins that are mentioned as complementing cytokine function and helping to regulate the adaptive and innate immune system?
What is the term used to describe the process of harvesting HSCs from the peripheral circulation?
What is the term used to describe the process of harvesting HSCs from the peripheral circulation?
What is the name of the disease that is often associated with the use of recombinant human erythropoietin?
What is the name of the disease that is often associated with the use of recombinant human erythropoietin?
What is the primary function of hematopoietic stem cells in a lethally irradiated host?
What is the primary function of hematopoietic stem cells in a lethally irradiated host?
What is the outcome of the experiment conducted by Till and McCulloch in 1961?
What is the outcome of the experiment conducted by Till and McCulloch in 1961?
What is the characteristic of colony-forming units–spleen (CFU-S)?
What is the characteristic of colony-forming units–spleen (CFU-S)?
What is the role of the common lymphoid progenitor?
What is the role of the common lymphoid progenitor?
What is the outcome of the differentiation of the common myeloid progenitor?
What is the outcome of the differentiation of the common myeloid progenitor?
What is the characteristic of undifferentiated HSCs?
What is the characteristic of undifferentiated HSCs?
What is the significance of the experiment conducted by Till and McCulloch in 1961?
What is the significance of the experiment conducted by Till and McCulloch in 1961?
What is the relationship between HSCs and progenitor cells?
What is the relationship between HSCs and progenitor cells?
Study Notes
Hematopoiesis
- Hematopoiesis in healthy adults is restricted primarily to the bone marrow.
- During fetal development, hematopoiesis occurs in the yolk sac, then in the aorta-gonad-mesonephros (AGM) region, and finally in the fetal liver.
- Hematopoiesis in the fetal liver reaches its peak by the third month of fetal development, then gradually declines after the sixth month, retaining minimal activity until 1 to 2 weeks after birth.
Mesoblastic Phase
- Hematopoiesis is considered to begin around the 19th day of embryonic development after fertilization.
- Cells from the mesoderm migrate to the yolk sac, where some form primitive erythroblasts.
- These cells pass through pores in the endothelial cytoplasm, are released into the vascular sinus, and then move into the peripheral circulation.
Hematopoietic Stem Cells (HSCs)
- HSCs are predominantly quiescent, maintained in a non-dividing state by intimate interactions with thrombopoietin-producing osteoblasts.
- HSCs are capable of self-renewal, are pluripotent, and can give rise to differentiated progeny.
- HSCs can reconstitute the hematopoietic system of a lethally irradiated host.
Stem Cell Theory
- The monophyletic theory is the most widely accepted theory among experimental hematologists, suggesting that all blood cell lineages are derived from a single progenitor stem cell called a pluripotent HSC.
- The polyphyletic theory suggests that each of the blood cell lineages is derived from its own unique stem cell.
HSCs and Cytokines
- HSCs can differentiate into progenitor cells committed to either lymphoid or myeloid lineages.
- The common lymphoid progenitor proliferates and differentiates into T, B, and natural killer lymphocyte and dendritic lineages.
- The common myeloid progenitor proliferates and differentiates into individual granulocytic, erythrocytic, monocytic, and megakaryocytic lineages.
- Cytokines and chemokines complement each other to regulate the adaptive and innate immune system.
Thymus Development
- Non-development of the thymus during gestation results in the lack of formation of T lymphocytes.
- Adults with thymic disturbance are not affected because they have developed and maintained a pool of T lymphocytes for life.
Clinical Applications
- Understanding the relationships between HSCs and their microenvironment is critical to the advancement of cell therapies based on HSCs, such as clinical marrow transplantation.
- A recent chemokine-related discovery has led to a successful transplantation-based HSC collection strategy targeting the HSC-microenvironment niche interaction to cause release of HSCs from the bone marrow compartment into the peripheral circulation.
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Description
This quiz covers the process of hematopoiesis during fetal development, including the role of the yolk sac and the aorta-gonad-mesonephros region.
