Formation of white blood cells
Leucopoiesis refers to the formation of leukocytes known as white blood cells . This process takes place in the bone marrow as part of blood formation. The synonym of leukopoiesis is called leukocytopoiesis . The process exists as a component of hematopoiesis. This is the technical term for blood formation. The white blood cells are formed from the stem cells in the bone marrow during the process.
The definition of leukocyte formation
In adult humans, leukocytes form in the red bone marrow during leukopoiesis . This is located in the breastbone and pelvis. Children also have the red bone marrow to produce blood in the tubular bones. These exist in the arms and legs.
The actual number of leukocytes is subject to strong fluctuations. It depends on the state of health of the body. Thus, there are between 4,000 and 10,000 white blood cells in one cubic milliliter of blood. These move actively. This gives them the opportunity to get from the bloodstream into the tissue. Their main task is to ward off pathogens and foreign bodies in the organism.
How are leukocytes formed?
In leukopoiesis, the leukocytes develop from the progenitor cells of the stem cells. Here the white blood cells are divided into different categories. Various types of leukocytes are thus formed. Their frequency depends on their task and functionality. In order for the respective white blood cells to fulfill their intended service, they imprint themselves in special organs after their formation.
In the lymphatic system, the leukocytes learn which substances are present in the body and which are foreign. This lymphatic system includes the lymph nodes, spleen, tonsils, thymus and bone marrow. The stem cells required for leukopoiesis exist as pluripotent elements. This means that they have the opportunity to develop differently.
If a stem cell divides during leukopoiesis, no two daughter cells are formed. Instead, another pluripotent stem cell and a progenitor cell form. The progenitor cell belongs to a single blood cell , a determined stem cell. This matures further in a later process. This maturation depends on the particular growth factor, cytokines. New blood is formed, so that the leukopoiesis is constantly repeated.
How is the formation of leukocytes divided?
Leucopoiesis ensures the constant supply of white blood cells. Therefore, this process proceeds without a break. Different types of cells are formed during this process. Thus, the leukopoiesis is divided into different areas. These include:
- die Monozytopoese,
- die Granulozytopoese
- and lymphopoiesis, also called lymphocytopoiesis.
The granulocytopoiesis as well as the monocytopoiesis exist as a part of the myelopoiesis. Their formation takes place without exception in the red bone marrow. In contrast, lymphopoiesis exists as a process in the lymphatic organs. Thus, lymphopoiesis exists as part of leukopoiesis. Here, the determined stem cells form from a lymphoid stem cell (CLP). This happens with the help of cytokines. This results in pro-B cells, pro-T cells and pro-NK cells.
The physiology of the process
When leukopoiesis begins, multipotent hematopoietic stem cells (MHS) exist. With these there is the possibility of dividing into different blood cells. If a cytokine – for example TPO – is added to the process, two types of stem cells develop. These exist as myeloid stem cells and lymphoid stem cells. If another differentiation follows, the stem cells commit themselves to the production of special cells . They no longer appear as multipotent cells. Instead, from that moment on, they act as oligopotent elements.
Myelopoiesis as part of leukocyte formation
Myelopoiesis exists as a type of leukopoiesis . Bi- and unipotent stem cells arise from a myeloid stem cell (CMP). These usually collect in cell colonies. Therefore they call themselves “colony-forming units”. The neutrophilic granulocytes develop from the bipotent stem cells . From these arise two unipotent stem cells. These are called myeloblast and monoblast.
If the myeloid stem cell exists as a unipotent specimen, eosinophilic granulocytes form from it . The end product is called the eosinophiloblast in technical jargon. If basophilic granulocytes develop from the unipotent stem cell , the result is called a basophiloblast. The actual white blood cells develop from these blasts in several steps during leukopoiesis. The division into different cell lines will take place later.
By forming these colonies of stem cells, called “pools,” leukopoiesis has numerous benefits for the body. Through this process, the organism reacts quickly and flexibly to an increased need for leukocytes. This is due to the fact that unipotent cells divide faster than the multipotent variant.
Summary:
Experts refer to the formation of white blood cells, which are also called leukocytes, as leukopoiesis. In this process, there are various sub-processes such as myelopoiesis. During formation, the different types of leukocytes are shaped and prepare for their future function.
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