Types

• Human bones contain two types of marrow: red and yellow bone marrow. Red marrow is composed of myeloid tissue which contains hemopoietic stem cells. Yellow bone marrow is made mostly of fat and contains stromal stem cells.
  An adult has nearly equal amounts of red and yellow marrow although we are born with only red marrow. Throughout childhood the body begins to produce yellow bone marrow and some of this red bone marrow is gradually replaced.
  
  

Function

• The primary function of bone marrow is to generate new blood cells, a process called hematopoiesis. Red blood cells, white blood cells and platelets are made in red bone marrow while some white blood cells, fat, bone and cartilage cells are formed by the yellow marrow. If a large volume of blood is lost, the body can change yellow bone marrow into red bone marrow to assist in blood cell production.
  
  

Identification

• Yellow bone marrow is located within the long bones of the legs and arms and owes its color to the high quantity of fat cells it contains. Red bone marrow resides in bones such as the hip bones, skull, vertebrae, shoulders and chest as well as the end of the leg and arm bones. Both types of marrow can be identified by their location, color and the type of cells they contain.
  
  

Considerations

• A number of diseases may occur from disorders of the bone marrow including cancer. Cancer of the bone marrow is called leukemia, which happens when bone marrow cells begin to multiply abnormally. There are many types of leukemia and they are categorized by the type of blood cell they impact. Most leukemia creates an excess of white blood cells in the body which then causes a lack of platelets and red blood cells as well as a severe strain on the immune system. There are a variety of treatments for leukemia including chemotherapy and radiation.
  
  

Potential

• Since its inception in 1968, bone marrow transplantation has been a viable treatment for severe stages of cancer and genetic diseases which cause irregular blood cell production. Bone marrow can be obtained from living donors matched to the transplant recipient. Bone marrow is harvested from the donor's hip under general anesthetic. Thousands of marrow transplants are conducted each year and that number is expected to rise.