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Megakaryocyte fragments and the microtubule coil

J M Radley1, M A Hartshorn

  • 1Biological Research Unit, Cancer Institute, Melbourne, Victoria, Australia.

Blood Cells
|January 1, 1987
PubMed

Insights

Megakaryocyte fragments break apart in vivo, suggesting platelets don't always form sequentially. Microtubule coils, common in circulating platelets, likely form after platelet liberation from megakaryocyte processes.

Area of Science:

  • Hematology
  • Cell Biology
  • Biophysics

Background:

  • Megakaryocytes are large bone marrow cells responsible for producing platelets.
  • Platelet formation (thrombopoiesis) is a complex process involving megakaryocyte fragmentation.
  • The precise mechanism and timing of platelet liberation remain incompletely understood.

Purpose of the Study:

  • To investigate the in vivo fragmentation of megakaryocyte process fragments.
  • To determine the structural characteristics of these fragments and their relation to platelet formation.
  • To elucidate the timing of microtubule coil formation in relation to platelet liberation.

Main Methods:

  • Incubation of bone marrow explants.
  • Observation of megakaryocyte process fragments.
  • Transmission electron microscopy (TEM) of fragments and putative platelets.

Main Results:

  • Megakaryocyte process fragments were observed migrating from bone marrow explants.
  • These fragments adopted a beaded form, resembling multiple platelets.
  • Microtubules were predominantly longitudinally oriented in fragments; coils were rare and terminal.
  • Marginal microtubule coils, characteristic of circulating platelets, were not consistently observed in liberated fragments.

Conclusions:

  • Platelet liberation from megakaryocytes may not always be a sequential process.
  • In vivo fragmentation of megakaryocyte processes occurs.
  • The characteristic marginal microtubule coil of platelets likely forms after their liberation from the megakaryocyte.

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