Metamyelocyte

Metamyelocyte is a stage in the development of a granulocyte, a type of white blood cell that plays a critical role in the immune system by helping to fight infection. Metamyelocytes are derived from myeloblasts through a series of developmental stages in the bone marrow. This cell stage is characterized by its distinct kidney-shaped nucleus and is considered a late stage in the maturation of granulocytes, preceding the band cell stage and ultimately maturing into a fully functional granulocyte.

Development

The development of granulocytes begins with the stem cell in the bone marrow, which differentiates into a myeloblast. The myeloblast then undergoes several stages of development: first becoming a promyelocyte, then a myelocyte, and after that, a metamyelocyte. The progression from myelocyte to metamyelocyte is marked by significant changes in cell morphology, including the condensation of chromatin and the beginning of nuclear segmentation, which gives the metamyelocyte its characteristic kidney-shaped nucleus.

Function

Metamyelocytes are not yet fully functional cells and remain in the bone marrow until they mature into band cells and eventually into mature granulocytes, which include neutrophils, eosinophils, and basophils. These mature cells are then released into the bloodstream, where they play a vital role in the body's immune response by identifying, engulfing, and destroying pathogens such as bacteria and viruses.

Clinical Significance

The presence of metamyelocytes in the peripheral blood can be an indicator of a process known as a "left shift," which occurs when there is an increased demand for granulocytes in the body, such as during an acute infection or inflammation. This can lead to the premature release of immature granulocytes, including metamyelocytes, into the bloodstream. Therefore, the detection of metamyelocytes outside of the bone marrow can be a useful diagnostic tool in assessing the body's response to infection or stress.

See Also

• Leukopoiesis
• Myeloid
• Hematopoiesis
• Granulopoiesis

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  Basophilic metamyelocyte
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  Eosonophilic metamyelocyte
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  Neutrophilic metamyelocyte
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  Hematopoiesis (human) diagram