Myeloblast

Myeloblast
Myeloblast
Identifiers
Code	TH H2.00.04.3.04002
Anatomical terminology []

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

These cells descend from the primitive reticulum cells, which are found in the stroma of the marrow. There is also an intermediate phase between the myeloblast and these primitive reticulum cell, namely the hemocytoblast. At this time several developing blood cell lines are available, like erythropoiesis and thrombopoiesis. The granulopoiesis is regulated by humoral agents, like colony-stimulating factor (CSF) and interleukin 3.

The myeloblasts reside extravascularly in the marrow. The hematopoiesis takes place in the extravascular cavities between the sinuses of the marrow. The wall of the sinuses is composed of two different types of cells, the endothelial cells and the adventitial reticular cells. The hemopoietic cells are aligned in cords or wedges between these sinuses, the myeloblasts and other granular progenitors are concentrated in the subcortical regions of these hemopoietic cords.

Myeloblasts are rather small cells with a diameter between 14 and 18μm. The major part is occupied by a large oval nucleus composed of very fine nonaggregated chromatin and possesses 3 or more nucleoli. The cytoplasm has basophilic character and is devoid of granules, which is a major difference with its successor, the promyelocyte. The nucleolus is the site of assembly of ribosomal proteins, which are located in various particles dispersed over the cytoplasm. are present but have a rather small size.

...
Wikipedia