Bone marrow is the permeable, soft tissue that lies within most of the bones of the human body. It is often confused with the spinal cord, but the two tissues are very different. It is safe to say that the bone marrow is the main organ responsible for hematopoiesis. It produces stem cells, which are the basis of the immune system. The bone marrow is also involved in many metabolic processes and is highly complex, performing many functions. It plays a key role in the formation of new blood cells, its mass is about 5% of the total human weight.
