Faculty/Retired
University of Minnesota
Department of Genetics, Cell Biology and Development
6-160 Jackson Hall
321 Church St SE
Minneapolis, MN 55455
Robert L. Sorenson, Ph.D.
Professor Emeritus
University of Minnesota
Department of Genetics, Cell Biology and Development
6-160 Jackson Hall
321 Church St SE
Minneapolis, MN 55455
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MH 034a-034bhr Bone Marrow Smear
Click the thumbnail to show this bone marrow smear (40x).
Megakaryocyte
Platelets develop from the multipotential myeloid stem cell (CFU-GEMM) which differentiates into the megakaryocyte progenitor cell (CFU-Meg).
Megakaryoblasts are produced directly from megakaryocyte progenitor cell (CFU-Meg). They are large cells (~30 µm diameter) with a round nucleus.
Megakaryocytes are produced from megakaryoblasts under the influence of thrombopoietin. They grow in size by replicating DNA without going through cytokinesis (endomitosis).
Megakaryocytes are the only recognizable precursor of platelets.
Large cells (50 to 70 µm diameter)
Large multilobed, polyploid nucleus (up to 32 copies of the normal complement of DNA)
Click the thumbnail to show this bone marrow smear at higher magnification (60x).
Platelets
Platelets are small cell fragments produced by budding of from megakaryocytes under the influence of thrombopoietin. Each megakaryocyte produces between 5,000 and 10,000 platelets.
Platelets are released from the bone marrow into the peripheral circulation. Too few platelets can cause excessive bleeding, while too many platelets can cause blood clot formation. Their life span is between 7 to 10 days.
A cross-section of a platelet is shown in EM 159 Platelet by transmission electron microscopy.
