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10.7: Platelets

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    Notes: Platelets are cytoplasmic fragmentations from a megakaryocyte. Fragmentation occurs by the megakaryocyte demarcation membrane system.1

    Nucleus-to-Cytoplasm Ratio: N/A2

    Nucleoli: N/A2

    Nucleus: N/A2


    Light blue to colourless

    Azurophilic granules present

    % in Bone Marrow: N/A

    % in Peripheral Blood: 7-25 per field (100x oil immersion field)

    Reticulated Platelets

    Immature platelets that contain an abundant amount of RNA.1

    Platelet Clumps and Satellitism

    Platelet satellitism is a phenomenon that can occur in vitro when a blood sample is collected in an EDTA anticoagulant tube. Platelets adhere to neutrophils by an antibody mediated process and this results in falsely decreased platelet counts.3,4

    Platelet clumping can also occur when blood is collected in an EDTA tube. Platelets become activated and aggregate. EDTA causes some cell antigens to be unmasked and react with antibodies in the serum.3,4

    In both cases, the issue may be corrected when blood samples are collected in sodium citrate anti-coagulated tubes.3,4


    1. Lynne Williams J. The Platelet. In: Clinical laboratory hematology. 3rd ed. New Jersey: Pearson; 2015. p. 144–53.

    2. Rodak BF, Carr JH. Megakaryocyte maturation. In: Clinical hematology atlas. 5th ed. St. Louis, Missouri: Elsevier Inc.; 2017. p. 31-40.

    3. Burns C, Dotson M. Hematology Procedures. In: Clinical laboratory hematology. 3rd ed. New Jersey: Pearson; 2015. p. 782-814.

    4. Clark KS, Hippe TGl. Manual, semiautomated, and point-of-care testing in hematology. In: Rodak’s hematology clinical applications and principles. 5th ed. St. Louis, Missouri: Saunders; 2015. p.187-207.

    This page titled 10.7: Platelets is shared under a CC BY-NC 4.0 license and was authored, remixed, and/or curated by Valentin Villatoro and Michelle To (Open Education Alberta) via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.