Promyelocyte

Promyelocyte in bone marrow smear

Promyelocyte is another stage of granulopoiesis after myeloblast. Its nucleus is still round with finechromatin and well visible nucleoli, but it is already beginning to flatten. The cytoplasm is still basophilic, it contains a proteosynthetic apparatus and so it is a stage that can still undergo mitosis. In the area of ​​the flattened nucleus, the so-called cytocentrum is already visible on well-stained slides as a lighter spot. We can distinguish between two types of promyelocytes:

• 1. grade, where Golgiho body forms non-specific granules surrounded by a membrane, stainable with azure. These azurophilic granules are essentially lysosomes – containing lysosomal enzymes and myeloperoxidase.
• 2. grade, whose Golgi body release first specific granules and thus it is already possible to determine whether the cell will specialize to become basophil, eosinophil or neutrophil.

Promyelocyte is the only stage of granulopoiesis in which azurophilic granules are formed. Therefore, their amount in the cytoplasm decreases with each cell division.

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Related articles

• Hematopoiesis (histology)

Literatured used

• LÜLLMANN, Renate – RAUCH,. Histologie. 1. edition. Praha : Grada, 2012. ISBN 978-80-247-3729-4.

• MESCHER, Anthony L – JUNQUEIRA, Luiz Carlos Uchôa. Junqueira's Basic Histology. 12. edition. United States : McGraw-Hill Education - Europe, 2009. 480 pp. ISBN 9780071630207.