Myelopoiesis
Encyclopedia
Myelopoiesis is the regulated formation of myeloid cells
, including eosinophilic granulocytes
, basophilic granulocytes
, neutrophilic granulocytes, and monocytes. In hematology
, myelopoiesis is the production of blood cells in the bone marrow
.
The myeloid
progenitor can differentiate in the bone marrow into granulocyte
s, macrophage
s (mature monocyte
s), mast cell
s (whose blood-borne progenitor is not well defined), and dendritic cell
s of the innate immune system. The granulocytes, also called polymorphonuclear leukocytes because of their oddly shaped nuclei, give rise to three short lived cell types including eosinophils, basophils, and neutrophils. A granulocyte differentiates into a distinct cell type by a process called granulopoiesis
. In this process it first transforms from a common myeloblast (myeloid progenitor) to a common promyelocyte. This promyelocyte gives rise to a unique myelocyte that for the first time can be classified as a eosinophil, basophil, or neutrophil progenitor based on the histological staining affinity (eosinophilic, basophilic, or neutral granules). The unique myelocyte next differentiates into a metamyelocyte and then a band cell
, with a "C" shaped nucleus, before becoming a mature eosinophil, basophil, or neutrophil. Macrophages come from monoblast progenitors that differentriate into promonocytes, which mature into monocytes. Monocytes eventually enter the tissues and become macrophages.
Myeloid
The term myeloid suggests an origin in the bone marrow or spinal cord, or a resemblance to the marrow or spinal cord.In hematopoiesis, the term "myeloid cell" is used to describe any leukocyte that is not a lymphocyte...
, including eosinophilic granulocytes
Eosinophilic
Eosinophilic refers to the staining of certain tissues, cells, or organelles after they have been washed with eosin, a dye.Eosin is an acidic dye; thus, the structure being stained is basic....
, basophilic granulocytes
Basophilic
Basophilic is a technical term used by histologists. It describes the microscopic appearance of cells and tissues, as seen down the microscope, after a histological section has been stained with a basic dye. The most common such dye is haematoxylin....
, neutrophilic granulocytes, and monocytes. In hematology
Hematology
Hematology, also spelled haematology , is the branch of biology physiology, internal medicine, pathology, clinical laboratory work, and pediatrics that is concerned with the study of blood, the blood-forming organs, and blood diseases...
, myelopoiesis is the production of blood cells in the bone marrow
Bone marrow
Bone marrow is the flexible tissue found in the interior of bones. In humans, bone marrow in large bones produces new blood cells. On average, bone marrow constitutes 4% of the total body mass of humans; in adults weighing 65 kg , bone marrow accounts for approximately 2.6 kg...
.
The myeloid
Myeloid
The term myeloid suggests an origin in the bone marrow or spinal cord, or a resemblance to the marrow or spinal cord.In hematopoiesis, the term "myeloid cell" is used to describe any leukocyte that is not a lymphocyte...
progenitor can differentiate in the bone marrow into granulocyte
Granulocyte
Granulocytes are a category of white blood cells characterized by the presence of granules in their cytoplasm. They are also called polymorphonuclear leukocytes because of the varying shapes of the nucleus, which is usually lobed into three segments...
s, macrophage
Macrophage
Macrophages are cells produced by the differentiation of monocytes in tissues. Human macrophages are about in diameter. Monocytes and macrophages are phagocytes. Macrophages function in both non-specific defense as well as help initiate specific defense mechanisms of vertebrate animals...
s (mature monocyte
Monocyte
Monocytes are a type of white blood cell and are part of the innate immune system of vertebrates including all mammals , birds, reptiles, and fish. Monocytes play multiple roles in immune function...
s), mast cell
Mast cell
A mast cell is a resident cell of several types of tissues and contains many granules rich in histamine and heparin...
s (whose blood-borne progenitor is not well defined), and dendritic cell
Dendritic cell
Dendritic cells are immune cells forming part of the mammalian immune system. Their main function is to process antigen material and present it on the surface to other cells of the immune system. That is, dendritic cells function as antigen-presenting cells...
s of the innate immune system. The granulocytes, also called polymorphonuclear leukocytes because of their oddly shaped nuclei, give rise to three short lived cell types including eosinophils, basophils, and neutrophils. A granulocyte differentiates into a distinct cell type by a process called granulopoiesis
Granulopoiesis
Granulopoiesis is hematopoiesis of granulocytes.It occurs primarily within bone marrow and involves the following stages:* Pluripotential hemopoietic stem cell* Myeloblast* Promyelocyte* Eosino/neutro/basophilic myelocyte...
. In this process it first transforms from a common myeloblast (myeloid progenitor) to a common promyelocyte. This promyelocyte gives rise to a unique myelocyte that for the first time can be classified as a eosinophil, basophil, or neutrophil progenitor based on the histological staining affinity (eosinophilic, basophilic, or neutral granules). The unique myelocyte next differentiates into a metamyelocyte and then a band cell
Band cell
A band cell is a cell undergoing granulopoiesis, derived from a metamyelocyte, and leading to a mature granulocyte.It is characterized by having a nucleus which is curved, but not lobar....
, with a "C" shaped nucleus, before becoming a mature eosinophil, basophil, or neutrophil. Macrophages come from monoblast progenitors that differentriate into promonocytes, which mature into monocytes. Monocytes eventually enter the tissues and become macrophages.