A promegakaryocyte is a
precursor cell for a
megakaryocyte
A megakaryocyte (''mega-'' + '' karyo-'' + '' -cyte'', "large-nucleus cell") is a large bone marrow cell with a lobated nucleus responsible for the production of blood thrombocytes (platelets), which are necessary for normal blood clotting. In ...
. It arises from a megakaryoblast, into a promegakaryocyte and then into a megakaryocyte, which will eventually break off and become a platelet.
The developmental stages of the megakaryocyte are:
CFU-Me (
pluripotential hemopoietic stem cell
Hematopoietic stem cells (HSCs) are the stem cells that give rise to other blood cells. This process is called haematopoiesis. In vertebrates, the very first definitive HSCs arise from the ventral endothelial wall of the embryonic aorta within t ...
or hemocytoblast) → megakaryoblast → promegakaryocyte → megakaryocyte.
When the megakaryoblast matures into the promegakaryocyte, it undergoes
endoreduplication
Endoreduplication (also referred to as endoreplication or endocycling) is replication of the nuclear genome in the absence of mitosis, which leads to elevated nuclear gene content and polyploidy. Endoreplication can be understood simply as a vari ...
and forms a promegakaryocyte which has multiple nuclei,
azurophilic granule
An azurophilic granule is a cellular object readily stainable with a Romanowsky stain. In white blood cells and hyperchromatin, staining imparts a burgundy or merlot coloration. Neutrophils in particular are known for containing azurophils load ...
s, and a basophilic cytoplasm. The promegakaryocyte has rotary motion, but no forward migration.
Promegakaryocytes and other precursor cells to megakaryocytes arise from pluripotential hematopoietic progenitors. The megakaryoblast is then produced, followed by the promegakaryocyte, the granular megakaryocyte, and then the mature megakaryocyte. When it is in its promegakaryocyte stage, it is considered an undifferentiated cell.
Megakaryocyte pieces will eventually break off and begin circulating the body as platelets. Platelets are very important because of their role in blood clotting, immune response, and the formation of new blood vessels.
References
External links
"Marrow aspirate, 10x. Promegakaryocyte" at ttuhsc.edu"Megakaryocytes: Promegakaryocyte" at bloodline.net
Immune system
Blood cells
{{cell-biology-stub