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A megakaryocyte (from mega- 'large' karyo- 'cell nucleus' and -cyte 'cell') is a large bone marrow cell with a lobated nucleus that produces blood platelets (thrombocytes), which are necessary for normal clotting. In humans, megakaryocytes usually account for 1 out of 10,000 bone marrow cells, but can increase in number nearly 10-fold during ...
The megakaryoblast has a high nucleus to cytoplasm ratio with a nucleus that may be 3 to 5 times the size of the cytoplasm. The nucleus is generally oval, kidney shaped or lobed. Several nucleoli are visible, along with loose chromatin. [10] The chromatin may vary from cell to cell, ranging from fine to heavy and dense.
For example, "blast" forms of erythrocytes, leukocytes, and megakaryocytes start with an N:C ratio of 4:1, which decreases as they mature to 2:1 or even 1:1 (with exceptions for mature thrombocytes and erythrocytes, which are anuclear cells, and mature lymphocytes, which only decrease to a 3:1 ratio and often retain the original 4:1 ratio). [1]
The megakaryoblast is a platelet precursor that undergoes endomitosis to form megakaryocytes that have 8 to 64 nuclei. Megakaryocytes shed platelets into the bloodstream. β1-tubulin microtubules, which are found in megakaryocytes, facilitate this process of shedding platelets into the bloodstream. [5]
The normal range (99% of population analyzed) for platelets is 150,000 to 450,000 per cubic millimeter. [6] If the number of platelets is too low, excessive bleeding can occur.
By comparison, one gram of hydrogen, a macroscopic system, has ~ 6 × 10 23 times [4] the mass–energy of a single proton, a central object of study in high energy physics.
The Maine Coon is easily twice the size of the smaller cat. Related: 60-Second Video of Maine Coon's Transformation From Kitten to Cat Is Wild This becomes particularly important toward the end of ...
Acute megakaryoblastic leukemia (AMKL) is life-threatening leukemia in which malignant megakaryoblasts proliferate abnormally and injure various tissues. Megakaryoblasts are the most immature precursor cells in a platelet-forming lineage; they mature to promegakaryocytes and, ultimately, megakaryocytes which cells shed membrane-enclosed particles, i.e. platelets, into the circulation.