Megakaryoblast (Draft with edits in Bold)[edit]

Megakaryoblast
Megakaryoblast
	Haematopoiesis
	Bone marrow smears of acute megakaryoblastic leukemia, with May-Grün-wald-Giemsa staining, ×100. (A) Cytoplasmic blebs (black arrow) and binucleated cell. (B) Cell cluster giving a pseudo-solid tumor aspect of AMKL.
	Anatomical terms of microanatomy [edit on Wikidata]

A megakaryoblast (mega- + karyo + -blast, "large-nucleus immature 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.^[1] The megakaryoblast is the beginning of the thrombocytic or platelet forming series.

Megakaryoblasts typically have a large oval-shaped nucleus or a nucleus that is lobed with many nuclei.^[2] The megakaryoblast resembles the myeloblast or lymphoblast morphologically, however the megakaryoblast varies in phenotype and the structure viewed with electron microscopy.^[2]^[3]

Increased amounts of megakaryoblasts in the bone marrow may indicate a disease state.^[4] An example of this is acute megakaryoblastic leukemia, which occurs when the level of megakaryoblasts in the bone marrow exceeds 20%.^[5]

Development[edit]

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 precurser cells. Two of the committed biomarkers are CD34- and CD150+.^[6] 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.^[7]

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.^[6]

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.^[6]

Structure[edit]

Megakaryoblasts can range from 6μm to 24μm in diameter.^[8] 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.^[2] 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.^[9]

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.^[2]

Associated Diseases[edit]

Acute megakaryoblastic leukemia

References[edit]

^ Martin, E. A.; Law, Jonathan, eds. (2020). Concise medical dictionary (OQR) and concise colour medical dictionary. Oxford quick reference (10th ed.). New York: Oxford University Press. ISBN 978-0-19-883661-2.
^ ^a ^b ^c ^d Kawthalkar, Shirish M (2012). Essentials Of Haematology. Internet Archive (2nd ed.). Jaypee Brothers Medical Publishers. p. 231. ISBN 978-93-5090-184-7.
^ Porwit, Anna; McCullough, Jeffrey; Erber, Wendy N. (2011). Blood and bone marrow pathology (2nd ed.). Edinburgh: Churchill Livingstone/Elsevier. ISBN 978-0-7020-3147-2.
^ Theml, Harald; Diem, Heinz; Haferlach, Torsten; Theml, Harald (2004). Color atlas of hematology: practical microscopic and clinical diagnosis; 32 tables. Thieme flexibooks (2nd Revised ed.). Stuttgart New York: Thieme. ISBN 978-3-13-673102-4.
^ Kawthalkar, Shirish M (2012). Essentials Of Haematology. Internet Archive (2nd ed.). Jaypee Brothers Medical Publishers. p. 256. ISBN 978-93-5090-184-7.
^ ^a ^b ^c Naeim, Faramarz (2018). Atlas of hematopathology: morphology, immunophenotype, cytogenetics, and molecular approaches (2nd ed.). Waltham, MA: Elsevier. ISBN 978-0-12-809843-1.
^ Kufe, Donald W.; Holland, James F.; Frei, Emil; American Cancer Society, eds. (2003). Cancer medicine 6 (6th ed.). Hamilton, Ont. ; Lewiston, NY: BC Decker. ISBN 978-1-55009-213-4.
^ McClatchey, Kenneth, ed. (2002). Clinical Laboratory Medicine. Lippincott Williams & Wilkins. p. 802. ISBN 0683307517.
^ Anderson, Shauna (2013). Anderson's Atlas of Hematology. Lippincott Williams & Wilkins. p. 129. ISBN 978-1469826363.

External links[edit]

Megakaryoblast Article Critique[edit]

*Underline = my edits

**Strike-through = original portions to be edited

Lead section[edit]

The introductory sentence is concise, however it could be worded in a smoother way with more detail
- “A megakaryoblast (mega- + karyo- + -blast, "large-nucleus immature cell") is a precursor cell to a promegakaryocyte~~, which in turn becomes a megakaryocyte during haematopoiesis~~. During thrombocytopoiesis, the promegakaryocyte matures into the form of a megakaryocyte. From the megakaryocyte, platelets are formed. The megakaryoblast It is the beginning of the thrombocytic series.”
The lead section has information that is not cited
- Citations to be added based on above information/alterations:
  - https://www-oxfordreference-com.ezproxy.plattsburgh.edu:2443/display/10.1093/acref/9780198836612.001.0001/acref-9780198836612-e-6031
  - https://ia800305.us.archive.org/7/items/EssentialsOfHaematology/Essentials_of_Haematology.pdf
The lead does not include of brief description of the article’s major sections
- These should include: Development (including stages of thrombocytopoiesis), structure, associated diseases, etc.
The information in the lead section is present in the article itself as well

Content[edit]

The content within the article is relevant to the topic
The article is up-to-date for the overall definition and understanding of the megakaryoblast
- However there is more recent information on diseases associated with these cells that should be included
Content to be added:
- Acute megakaryoblastic leukemia
  - https://ia800305.us.archive.org/7/items/EssentialsOfHaematology/Essentials_of_Haematology.pdf
  - https://rlmc.edu.pk/themes/images/gallery/library/books/Pathology/Color_Atlas_of_Hematology__Practical_Microsc.pdf
- Possible links to other diseases
The section on “Development” is missing information and the content there has issues
- Issues with the section on “Development”
  - Abbreviations without the full term used
  - Uses the nonspecific reference of “some sources”
- This section will be corrected with updated information using the sources:
  - https://ia800305.us.archive.org/7/items/EssentialsOfHaematology/Essentials_of_Haematology.pdf
  - https://rlmc.edu.pk/themes/images/gallery/library/books/Pathology/Color_Atlas_of_Hematology__Practical_Microsc.pdf
  - https://www.sciencedirect.com/topics/immunology-and-microbiology/megakaryoblast
  - https://www.cartercenter.org/resources/pdfs/health/ephti/library/lecture_notes/med_lab_tech_students/ln_hematology_mlt_final.pdf
The section on “Structure” is concise, but it could be worded differently for a better flow.
- “These cells tend to range from ~~8 μm~~ 10 μm to 30 μm, ~~owing to the variation in size between different megakaryoblasts.~~”
- This section could also have some information added to aid in how it can be differentiated from other cells, along with more detail on various characteristics of megakaryoblasts
  - Sources to add more detail in “Structure” section:
    - https://www.cartercenter.org/resources/pdfs/health/ephti/library/lecture_notes/med_lab_tech_students/ln_hematology_mlt_final.pdf
    - https://ia800305.us.archive.org/7/items/EssentialsOfHaematology/Essentials_of_Haematology.pdf

Tone and Balance[edit]

The article is written in a neutral tone that does not appear biased in any particular direction, nor does it over or under represent any concepts
The article does not appear to make attempts to persuade the reader in favor of or away from a certain position

Sources and References[edit]

Within the article, there are three references and only three citations total
- This indicates that some of the facts may not be properly cited due to the low number of citations
All three references listed are different textbooks with content related to the topic
- These sources are thorough, however there are other sources available on megakaryoblasts that may be used to further develop the topic with proper references
For the knowledge available on megakaryoblasts at this time, the references used may still be considered current and relevant
Looking into megakaryoblasts, the majority of information available is in various scholarly textbooks, though there may be other peer-reviewed articles available on the topic as well

Organization and writing quality[edit]

Mostly the article is clear and concise, however there are some sentences that should be worded more clearly
- Notes have been made previously in this critique regarding unclear sections
There are no obvious spelling errors
Some grammatical errors have already been noted in this critique
The organization of the article could be improved by discussing the structure of megakaryoblasts before the development of them

Images and Media[edit]

The article does include images that enhance the understanding of the topic
- The diagram of hematopoiesis is particularly helpful in showing where megakaryoblasts fall in this process
- The image of bone marrow smears showing acute megakaryoblastic leukemia is helpful to show the structure, though a non disease state image may be more beneficial
The images provided appear to be well captioned and laid out in a visually appealing way
Both images adhere to Wikipedia’s copyright regulations as both have a CC BY-SA free license

Talk page discussion[edit]

There are no listed conversations under the talk page discussion
The article is rated as “Start-class” based on Wikipedia’s content assessment scale
This article is listed as of interest to: Physiology, Molecular Biology, and Anatomy
- It was also the subject of a Wiki Education Foundation-supported course assignment in the fall of 2021 for Bio 401 Cell Biology at SUNY Plattsburgh

Overall impressions[edit]

Overall, this article is incomplete and has room for improvement
- The information within this article already is accurate and provides a good starting point
The images and information in this article are both strengths aiding in the understanding of the topic
The areas of improvement for this article are in the organization of it, which was discussed already
- There are also a few grammatical errors in this article to be corrected
For the information available on megakaryoblasts, this article has a good start, but can be improved by adding information from more sources

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Bibliography sandbox

[1] Martin, E. A.; Law, Jonathan, eds. (2020). Concise medical dictionary (OQR) and concise colour medical dictionary. Oxford quick reference (10th ed.). New York: Oxford University Press. ISBN 978-0-19-883661-2.

[:0-2] Kawthalkar, Shirish M (2012). Essentials Of Haematology. Internet Archive (2nd ed.). Jaypee Brothers Medical Publishers. p. 231. ISBN 978-93-5090-184-7.

[3] Porwit, Anna; McCullough, Jeffrey; Erber, Wendy N. (2011). Blood and bone marrow pathology (2nd ed.). Edinburgh: Churchill Livingstone/Elsevier. ISBN 978-0-7020-3147-2.

[4] Theml, Harald; Diem, Heinz; Haferlach, Torsten; Theml, Harald (2004). Color atlas of hematology: practical microscopic and clinical diagnosis; 32 tables. Thieme flexibooks (2nd Revised ed.). Stuttgart New York: Thieme. ISBN 978-3-13-673102-4.

[5] Kawthalkar, Shirish M (2012). Essentials Of Haematology. Internet Archive (2nd ed.). Jaypee Brothers Medical Publishers. p. 256. ISBN 978-93-5090-184-7.

[:1-6] Naeim, Faramarz (2018). Atlas of hematopathology: morphology, immunophenotype, cytogenetics, and molecular approaches (2nd ed.). Waltham, MA: Elsevier. ISBN 978-0-12-809843-1.

[7] Kufe, Donald W.; Holland, James F.; Frei, Emil; American Cancer Society, eds. (2003). Cancer medicine 6 (6th ed.). Hamilton, Ont. ; Lewiston, NY: BC Decker. ISBN 978-1-55009-213-4.

[8] McClatchey, Kenneth, ed. (2002). Clinical Laboratory Medicine. Lippincott Williams & Wilkins. p. 802. ISBN 0683307517.

[9] Anderson, Shauna (2013). Anderson's Atlas of Hematology. Lippincott Williams & Wilkins. p. 129. ISBN 978-1469826363.

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