Promyelocytes: What Are They?

What Are Promyelocytes?

Basically, promyelocytes are known to be cells that are larger than a myeloblast which contains a prominent nucleoli, a Golgi hof and granules.

They are somehow different from a myeloblast as a myeloblast is a large cell which has a high N:C ratio – moderately blue cytoplasm and prominent nucleoli whereas a promyelocyte cell is larger than a myeloblast with a prominent nucleoli, a Golgi hof and granules – primary granules that appear reddish purple. Promyelocytes cannot be distinguished by routine light microscopy. (Source: “Promyelocyte” from Science Direct; https://www.sciencedirect.com/topics/immunology-and-microbiology/promyelocyte)

To add to that, promyelocytes have basophilic cytoplasm that contains primary (azurophilic) granules. A Golgi zone in promyelocyte may appear as a visible paranuclear hof or clearing. (Source: “Promyelocyte” by Teresa Scordino MD from American Society of Hematology; https://imagebank.hematology.org/image/60399/promyelocyte)

Promyelocytes comprise approximately of 2% of nucleated cells in the bone marrow. They appear to be dark blue/purple in color with often a single brightening at the edge of the nucleus or golgi zone. Promyelocytes are the youngest variant of the granulocyte series that can still be reasonably seen in peripheral blood in severe functions. (Source: “Neutrophil Promyelocyte from Cell Wiki)

Promyelocytes measure approximately 12 to 20 microns and will have a gritty basophilic color and texture and there will also be prominent primary granules that look red/purple grains of sand. (Source: “Promyelocyte” from LabCE.com; https://www.labce.com/spg448405_promyelocyte.aspx)

Source: * “Promyelocyte” from Science Direct; https://www.sciencedirect.com/topics/immunology-and-microbiology/promyelocyte)

* “Promyelocyte” by Teresa Scordino MD from American Society of Hematology; https://imagebank.hematology.org/image/60399/promyelocyte

* “Neutrophil Promyelocyte” from Cell Wiki; https://www.cellwiki.net/en/cells/granulocytes-neutrophil-promyelocyte

* Source: “Promyelocyte” from LabCE.com; https://www.labce.com/spg448405_promyelocyte.aspx