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 and developing into the myelocyte. 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 Nucle ...

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. The ...

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 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 roles in r ...

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 tissue found within the 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 is composed of hematopoietic ce ...

smear from a patient with acute promyelocytic leukemia, 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:

bone marrow Bone marrow is a semi-solid tissue found within the 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 is composed of hematopoietic ce ...

smear, promyelocyte and

erythroblast A nucleated red blood cell (NRBC), also known by several other names, is a red blood cell that contains a cell nucleus. Almost all vertebrate organisms have hemoglobin-containing cells in their blood, and with the exception of mammals, all of t ...

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