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The demarcation membrane system of the megakaryocyte: a misnomer?

J M Radley, C J Haller

    Blood
    |July 1, 1982
    PubMed

    Insights

    The demarcation membrane system in megakaryocytes provides membrane reserve for platelet formation, not for delineating mature platelets. This invaginated membrane system supports process extension and platelet envelopment.

    Area of Science:

    • Cell Biology
    • Hematopoiesis
    • Megakaryocyte Biology

    Background:

    • The demarcation membrane system (DMS) in megakaryocytes has been traditionally viewed as delineating developing platelets.
    • Its precise function during thrombopoiesis remains a subject of investigation.

    Purpose of the Study:

    • To investigate the role of the demarcation membrane system in megakaryocyte morphology and platelet formation.
    • To determine if the DMS delineates platelets or serves another function during thrombopoiesis.

    Main Methods:

    • Short-term culture of mouse bone marrow megakaryocytes.
    • Electron microscopy to examine megakaryocyte ultrastructure.
    • Treatment with microtubule depolymerizing agents to observe morphological changes.

    Main Results:

    • Mature megakaryocytes exhibited attenuated processes with limited invaginated membrane.
    • Exposure to microtubule depolymerizing agents caused process retraction and reappearance of extensive demarcation membrane.
    • These findings suggest the DMS acts as a membrane reserve.

    Conclusions:

    • The demarcation membrane system functions as a membrane reserve, evaginating to form attenuated processes that envelop nascent platelets.
    • The system does not primarily demarcate platelets within the maturing megakaryocyte.
    • The term "invaginated membrane system" is proposed as a more accurate descriptor than "demarcation membrane system."

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