A promyelocyte (or progranulocyte) is a

granulocyte Granulocytes are cells in the innate immune system characterized by the presence of specific granules in their cytoplasm. Such granules distinguish them from the various agranulocytes. All myeloblastic granulocytes are polymorphonuclear. They ha ...

precursor, developing from the

myeloblast The myeloblast is a unipotent stem cell which differentiates into the effectors of the granulocyte series. It is found in the bone marrow. Stimulation of myeloblasts by G-CSF and other cytokines triggers maturation, differentiation, proliferation ...

and developing into the

myelocyte A myelocyte is a young cell of the granulocytic series, occurring normally in bone marrow (can be found in circulating blood when caused by certain diseases). Structure When stained with the usual dyes, the cytoplasm is distinctly basophil ...

. Promyelocytes measure 12-20 microns in diameter. The

nucleus Nucleus ( : nuclei) is a Latin word for the seed inside a fruit. It most often refers to: * Atomic nucleus, the very dense central region of an atom *Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA Nucl ...

of a promyelocyte is approximately the same size as a myeloblast but their

cytoplasm In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. ...

is much more abundant. They also have less prominent

nucleoli The nucleolus (, plural: nucleoli ) is the largest structure in the nucleus of eukaryotic cells. It is best known as the site of ribosome biogenesis, which is the synthesis of ribosomes. The nucleolus also participates in the formation of s ...

than myeloblasts and their

chromatin Chromatin is a complex of DNA and protein found in eukaryote, eukaryotic cells. The primary function is to package long DNA molecules into more compact, denser structures. This prevents the strands from becoming tangled and also plays important ...

is more coarse and clumped. The cytoplasm is basophilic and contains primary red/purple granules.

Additional images

File:Cytology of acute promyelocytic leukemia, annotated.png,

Bone marrow Bone marrow is a semi-solid biological tissue, tissue found within the Spongy bone, spongy (also known as cancellous) portions of bones. In birds and mammals, bone marrow is the primary site of new blood cell production (or haematopoiesis). It i ...

smear from a patient with

acute promyelocytic leukemia Acute promyelocytic leukemia (APML, APL) is a subtype of acute myeloid leukemia (AML), a cancer of the white blood cells. In APL, there is an abnormal accumulation of immature granulocytes called promyelocytes. The disease is characterized ...

, showing characteristic abnormal promyelocytes.Image by Mikael Häggström, MD. Reference for findings: Last author update: 1 February 2013
Source image: :File:Faggot cell in AML-M3.jpg fro
PEIR Digital Library (Pathology image database)
(Public Domain) File:Hematopoiesis (human) diagram en.svg, Hematopoiesis File:Basophilic promyelocyte.png, Basophilic promyelocyte File:Eosonophilic promyelocyte.png, Eosonophilic promyelocyte File:Neutrophilic promyelocyte.png, Neutrophilic promyelocyte

References

External links

* - "18. Bone Marrow and

Hemopoiesis Haematopoiesis (, from Greek , 'blood' and 'to make'; also hematopoiesis in American English; sometimes also h(a)emopoiesis) is the formation of blood cellular components. All cellular blood components are derived from haematopoietic stem cell ...

bone marrow Bone marrow is a semi-solid biological tissue, tissue found within the Spongy bone, spongy (also known as cancellous) portions of bones. In birds and mammals, bone marrow is the primary site of new blood cell production (or haematopoiesis). It i ...

smear, promyelocyte and erythroblasts " * "Bone marrow" * "Bone marrow"
"White Cell Basics: Maturation" at virginia.edu
* - "Bone marrow smear" * Blood cells Leukocytes {{Cell-biology-stub