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Questions and Answers
What increases as the cell matures in megakaryopoiesis?
What increases as the cell matures in megakaryopoiesis?
Which of the following is NOT a recognizable stage in megakaryopoiesis?
Which of the following is NOT a recognizable stage in megakaryopoiesis?
Which zone of the platelet ultrastructure is responsible for maintaining the shape of the platelet?
Which zone of the platelet ultrastructure is responsible for maintaining the shape of the platelet?
What is the primary function of platelets in the body?
What is the primary function of platelets in the body?
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Which hormones and cytokines are involved in megakaryopoiesis?
Which hormones and cytokines are involved in megakaryopoiesis?
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What can be observed and differentiated under the microscope in a bone marrow specimen during megakaryopoiesis?
What can be observed and differentiated under the microscope in a bone marrow specimen during megakaryopoiesis?
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What is the main difference between BFU-Meg and CFU-Meg?
What is the main difference between BFU-Meg and CFU-Meg?
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What occurs at the LD-CFU-Meg stage in megakaryopoiesis?
What occurs at the LD-CFU-Meg stage in megakaryopoiesis?
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Which blood component is considered most significant for hemostasis?
Which blood component is considered most significant for hemostasis?
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What is unique about endomitosis in megakaryocytes?
What is unique about endomitosis in megakaryocytes?
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What is the primary goal of hemostasis in the body?
What is the primary goal of hemostasis in the body?
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In megakaryopoiesis, what is the maturation series specifically committed to producing?
In megakaryopoiesis, what is the maturation series specifically committed to producing?
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What is the main function of synthetic thrombopoietin?
What is the main function of synthetic thrombopoietin?
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Which cytokine acts in synergy with TPO?
Which cytokine acts in synergy with TPO?
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What is the role of phospholipids in the platelet membrane?
What is the role of phospholipids in the platelet membrane?
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How do inhibitors like PF4 and B-TG affect platelets?
How do inhibitors like PF4 and B-TG affect platelets?
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What is the consequence of having too many platelets in the body?
What is the consequence of having too many platelets in the body?
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At which stage of Megakaryopoiesis is the nucleus multilobed?
At which stage of Megakaryopoiesis is the nucleus multilobed?
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Which phospholipid ensures that only an ample amount of platelets should be present within the body?
Which phospholipid ensures that only an ample amount of platelets should be present within the body?
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In which stage of Megakaryopoiesis do cytoplasmic bluish-stained granules become visible?
In which stage of Megakaryopoiesis do cytoplasmic bluish-stained granules become visible?
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Which stage of Megakaryopoiesis shows evidence of endomitosis?
Which stage of Megakaryopoiesis shows evidence of endomitosis?
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Which Megakaryopoiesis stage has a 1:2 N:C ratio?
Which Megakaryopoiesis stage has a 1:2 N:C ratio?
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Which Megakaryocyte stage has a diameter of 30-50um?
Which Megakaryocyte stage has a diameter of 30-50um?
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What is the purpose of sequestering platelets in the spleen?
What is the purpose of sequestering platelets in the spleen?
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After platelets are released, what do megakaryocytes transform into?
After platelets are released, what do megakaryocytes transform into?
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What is thrombopoietin's role in platelet regulation?
What is thrombopoietin's role in platelet regulation?
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Why is the plasma concentration of Thrombopoietin inversely proportional to platelet and megakaryocyte mass?
Why is the plasma concentration of Thrombopoietin inversely proportional to platelet and megakaryocyte mass?
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Which zone of a platelet serves as the regulator for collecting substances needed for clot formation?
Which zone of a platelet serves as the regulator for collecting substances needed for clot formation?
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What happens to the 'naked megakaryocytes' after they are phagocytized by macrophages?
What happens to the 'naked megakaryocytes' after they are phagocytized by macrophages?
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Study Notes
Megakaryopoiesis Overview
- Cell maturation in megakaryopoiesis is characterized by the increase in cell size and nuclear lobulation.
- BFU-Meg (Burst Forming Unit-Megakaryocyte) and CFU-Meg (Colony Forming Unit-Megakaryocyte) are two critical stages, with BFU-Meg being less differentiated than CFU-Meg.
Stages of Megakaryopoiesis
- Recognizable stages include promegakaryocyte, megakaryocyte, and mature platelet stages.
- The LD-CFU-Meg stage is where cytoplasmic differentiation and increased ploidy occur.
Platelet Structure and Function
- The dense tubular system zone in platelet ultrastructure maintains platelet shape.
- Platelets primarily function in hemostasis, helping to form clots and stop bleeding.
Hormones and Cytokines
- Thrombopoietin (TPO) and various cytokines such as IL-6 and IL-11 are involved in megakaryopoiesis.
- TPO stimulates megakaryocyte development; its plasma concentration inversely correlates with platelet and megakaryocyte mass.
Microscopic Observations
- Bone marrow specimens during megakaryopoiesis show differentiation stages and morphology changes under the microscope.
- Cytoplasmic bluish-stained granules become visible in the promegakaryocyte stage.
Endomitosis and Nucleus Characteristics
- Endomitosis in megakaryocytes results in polyploidy without cell division, leading to larger cell size and further maturation.
- At the megakaryocyte stage, the nucleus appears multilobed with a 1:2 nucleus-to-cytoplasm (N:C) ratio.
Platelet Regulation and Effects of Imbalance
- Synthetic thrombopoietin promotes increased platelet production.
- Inhibitors like PF4 and beta-thromboglobulin can negatively affect platelet activation and aggregation.
Spleen Role and Megakaryocyte Transformation
- Sequestering platelets in the spleen serves to regulate platelet levels and prevent excessive clotting.
- After platelet release, megakaryocytes transform into smaller, less functional counterparts as they undergo senescence.
Consequences of Excess Platelets
- Having too many platelets can lead to thrombotic conditions, increasing the risk of clot events.
- Phagocytized 'naked megakaryocytes' are cleared by macrophages, affecting the overall megakaryocyte population in the marrow.
Summary of Key Stages
- The promegakaryocyte stage has an observable increase in granules.
- The megakaryocyte stage has a diameter of 30-50 µm and is characterized by distinct morphological changes.
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Description
Test your knowledge on the stages of Megakaryopoiesis, including MK-I and MK-II. Identify the characteristics and features of each stage, such as nucleus shape, granules, and mitosis type.
