Bone marrow is found in the centers of the bone, in the part known as the medullary cavity, and the bone marrow is the part responsible for the manufacture of blood cells during a process known medically as hematopoiesis. It is noteworthy that this process occurs in most of the bones during childhood, but in adulthood it is concentrated in the flat bones, so that it occurs mainly in the sternum, the spine, and the ilium bone , and as for the color of the bone marrow; It depends on the occurrence of the process of hematopoiesis, in other words the bone marrow in which blood cells are formed appears red due to the formation of red blood cells , and in contrast the bone marrow that does not form cells appears in yellow.  
As for the process of cell formation; It occurs with the beginning of the division of the hematopoietic stem cell , to produce two cells, one of which remains in the bone marrow to complete its functions, and the second undergoes a series of growth and development processes to become an adult and then leaves the marrow into the bloodstream, and the hematopoietic stem cells are distinguished by being able Accordingly, it can be said that hematopoietic stem cells are found in the bone marrow responsible for producing blood cells, and in contrast there is a type of cells known as mesenchymal stem cells found in the bone marrow that is not responsible for Manufacture of blood cells.  
Bone marrow cells
Bone marrow consists of stem cells as mentioned above, including hematopoietic, including mesenchymal, and these cells are differentiated into other types responsible for performing many important functions. It is divided into three main types, which are red blood cells responsible for transporting oxygen to the various cells of the body, and white blood cells responsible for facing various types of infection and the diseases that face The body, and the third type is the platelets, which are responsible for forming blood clots when a person is exposed to a wound in order to stop the bleeding, and as soon as these cells reach the bloodstream; It quickly does its job perfectly. 
As for mesenchymal stem cells, they differentiate into different groups of cells, which are the chondrocyte, the osteoblast cell, the osteoclast or osteoclast cell, and the adipocyte cell. , Myocyte, macrophage, endothelial cells, and fibroblast or young fibroblast cells. 
Bone marrow diseases
There are many diseases and health problems that can affect the bone marrow, the most important of which can be summarized as follows: 
- Leukemia: or leukemia , and it can be acute or chronic, and is represented by the infection of red blood cells of any kind with cancer, and the cells affected by cancer lose their ability to carry out their functions of attacking infection and disease resistance, as mentioned above, and the accumulation of white blood cells Their production is inhibited, as well as the production of red blood cells and platelets.
- Reproduction disease myeloma: , is a group of health problems that are excessive production of some one type of immature cells or mature cells derived from primitive cells, and these types of health problems:
- Leukemia medullary chronic or leukemia , chronic myeloid .
- True polycythemia (Latin: Polycythaemia vera).
- Primary or essential thrombocytosis.
- Myelodysplastic Syndrome: This disease is characterized by an imbalance in the production of bone marrow cells, and the health problems that result from suffering from this disease: anemia, infection , and frequent bleeding And the appearance of bruises.
- Anemia: It has many types related to the bone marrow, including Aplastic anemia, which occurs as a result of a defect in the stem cells or an injury to the bone marrow with some damage, and this type of anemia may appear as a result of other factors, such as genetic causes, Or exposure to radiation, or chemicals such as benzene, or as a result of taking some types of medicine. Other types of anemia that are associated with the bone marrow include: anemia due to a deficiency of vitamin B12, iron, or folate.
Bone marrow transplant
The bone marrow transplant is done by injecting the person concerned with healthy stem cells intravenously, and the most important reasons that explain resorting to bone marrow transplantation can be explained as follows: 
- With a bone marrow transplant, it is possible to replace the damaged or damaged bone marrow with a healthy one, in many health conditions, including cases of leukemia , cases of suffering from sickle cell anemia , and aplastic anemia.
- A bone marrow transplant can replenish the body's immune system to enable it to get rid of cancer cells that chemotherapy or radiation cannot get rid of.
- Through this process, the bone marrow can return to normal after exposure to radiation or chemotherapy given in the event that a person has cancer.
- Genetically healthy bone marrow transplantation can prevent the progression of some genetic diseases and prevent them from causing further damage, and these diseases include: Hurler syndrome, adrenal malnutrition and white brain .
- ^ A b t " of Bone Marrow" , Www.immunology.org , Retrieved July 20, 2018. Edited by .
- ^ A b t w "Trade shows All You Need To Know About Bone Marrow" , www.medicalnewstoday.com The , Retrieved July 20, 2018. Edited by .
- ↑ "Bone Marrow Disorders" , labtestsonline.org , Retrieved July 20, 2018. Edited.