biology

Megakaryoblast

Megakaryoblast is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Megakaryoblast rather than just read about it. In short: A megakaryoblast (from mega- 'large', karyo- 'cell nucleus' and -blast 'precursor cell') is a precursor cell to a promegakaryocyte. During thrombopoiesis, the promegakaryocyte matures into the form of a megakaryocyte.

Key takeaways

Megakaryoblast belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Megakaryoblast to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Megakaryoblast from memory before moving on to harder problems.

Reference excerpt

A megakaryoblast (from mega- 'large', karyo- 'cell nucleus' and -blast 'precursor cell') is a precursor cell to a promegakaryocyte. During thrombopoiesis, the promegakaryocyte matures into the form of a megakaryocyte. From the megakaryocyte, platelets are formed. The megakaryoblast is the beginning of the thrombocytic series or platelet forming series. Megakaryoblasts typically have a large oval-shaped nucleus or a nucleus that is lobed with many nuclei. The megakaryoblast resembles the myeloblast or lymphoblast morphologically; however the megakaryoblast varies in phenotype and the structure viewed with electron microscopy. Increased amounts of megakaryoblasts in the bone marrow may indicate a disease state. An example of this is acute megakaryoblastic leukemia, which occurs when the level of megakaryoblasts in the bone marrow exceeds 20%.

Development The megakaryocyte develops through the following lineage:

CFU-Meg (hematopoietic stem cell/hemocytoblast) → megakaryoblast → promegakaryocyte → megakaryocyte The megakaryoblast is derived from colony forming units (CFU-Meg) of hematopoietic stem cells found in red bone marrow. There are biomarkers found on the surface of hemopoietic stem cells that are used as identifiers for megakaryoblasts and other precursor cells. Two of the committed biomarkers are CD34- and CD150+. The CFU-Meg, which forms megakaryoblasts, is derived from the colony forming units that form myeloid cells (CFU-GEMM). The CFU-GEMM is also referred to as common myeloid progenitor cells giving rise to various hemopoietic cell lines. Once formed, megakaryoblasts become promegakaryocytes through one or two cycles of endomitosis, which is the division of chromosomes without the cell dividing via cytokinesis. Endomitosis creates cells with one nucleus and multiple chromosome copies. The promegakaryocytes continue the process of endomitosis, which results in the formation of granular megakaryocytes as the nucleus forms lobes with increased volumes. The megakaryocytes release the platelets into the blood stream. The process of platelet production, beginning with the formation of megakaryoblasts, takes about 7 days. Once in the blood stream, platelets last about 8 to 10 days.

Structure Megakaryoblasts can range from 6μm to 24μm in diameter. The megakaryoblast has a high nucleus to cytoplasm ratio with a nucleus that may be 3 to 5 times the size of the cytoplasm. The nucleus is generally oval, kidney shaped or lobed. Several nucleoli are visible, along with loose chromatin. The chromatin may vary from cell to cell, ranging from fine to heavy and dense. The cytoplasm is generally basophilic agranular (lacking granules) and will usually stain blue. Megakaryoblasts tend to be smaller in size and lacking granules, though the larger cells may contain fine granules. Compared to megakaryoblasts, promegakaryocytes and granular megakaryocytes are both larger and contain less basophilic cytoplasm with granules. Promegakaryocytes are usually about 15μm to 30μm in diameter with a lobed nucleus and some azurophil granules within moderately basophilic cytoplasm. Granular megakaryocytes are typically 40μm to 60μm in diameter with a large multi-lobed nucleus and an abundance of azurohpil granules within slightly basophilic cytoplasm.

Associated Diseases Acute megakaryoblastic leukemia

References

External links Photo Photo Photo Life cycle

Illustrations

Worked examples

Example 1 — a first encounter with Megakaryoblast

Start with the simplest possible case. Write down what Megakaryoblast claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Megakaryoblast before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Megakaryoblast ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Megakaryoblast

In research: Megakaryoblast appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Megakaryoblast in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Megakaryoblast is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cell biology stubs, Leukocytes, so understanding it makes those chapters shorter.
In everyday life: Look for Megakaryoblast outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Megakaryoblast in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Megakaryoblast means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Megakaryoblast out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Megakaryoblast in simple terms?

Why does Megakaryoblast matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Megakaryoblast?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Megakaryoblast.