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Platelet Disorders Douglas Triplett
Published in Genesio Murano, Rodger L. Bick, Basic Concepts of Hemostasis and Thrombosis, 2019
Platelets are produced by fragmentation of giant, multinucleated cells called megakaryocytes, which constitute less than 1% of the nucleated elements of the normal human bone marrow. Megakaryocytes arise from the multipotential stem cell, which is capable of differentiating into the erythrocytic, myelocytic, and megakaryocytic series.171 The earliest recognizable member of the megakaryocytic series is the megakar-yoblast. It is characterized by deeply basophilic cytoplasm and irregular nucleus with a loose chromatin pattern and several nucleoli. Megakaryoblasts typically have a diameter of 20 to 30 μηι. In contrast to other elements of the bone marrow, as the megakaryocyte matures there is nuclear division with an absence of cytoplasmic division; a process that is known as endomitosis. As a result, the nucleus becomes more lobulated and pyknotic, and the cytoplasm will increase in quantity and become more eosinophilic and granular. With each nuclear division, the ploidy doubles until the full complement is reached. In a normal marrow, approximately two thirds of the megakaryocytes are 16N (8 nuclear lobes), approximately one fourth are 32N (16 nuclear lobes), and the remainder are 8N (4 nuclear lobes). With the appropriate thrombo-poietic stimulus, ploidy may reach 64 or 128N. The morphologic classification applied to the maturing megakaryocytic series includes: megakaryoblasts for the earliest recognized form, promegakaryocyte or basophilic megakaryocyte for the intermediate forms, and mature (eosinophilic or granular) megakaryocyte for the late forms.
Apoptosis is one cause of thrombocytopenia in patients with high-altitude polycythemia
Published in Platelets, 2023
Zhuoya Wang, Noryung Tenzing, Qiying Xu, Huifang Liu, Yi Ye, Yi Wen, Tana Wuren, Sen Cui
Bone marrow smear by bone marrow aspirate were collected from patients with HAPC (HAPC group; n = 55) and from patients with leukemia who had achieved complete remission more than 2 years after chemotherapy and whose bone marrow smears were taken more than 3 months after the last chemotherapy (control group; n = 25). All participants were hospitalized in Qinghai University Affiliated Hospital from 1 January 2017, to 31 May 2021, and came from high-altitude areas (2,500–4,500 m). All megakaryocytes (MKs) were counted on films from a 1.5 × 3.0-cm bone marrow smear stained with Wright’s stain and classified as megakaryoblast (stage I), promegakaryocyte (stage II), granular MK (stage III), or mature MK (stage IV) [16].