The two types of bone marrow are red and yellow, according to Medscape. Yellow marrow contains a preponderance of fat, while red marrow contains less fatty tissue and aids in the creation and development of red blood cells.
Bone marrow is responsible for producing new blood cells, as well as fat, cartilage, and bone, according to Medical News Today. Bone marrow tissue that produces blood cells is called hemopoietic and is red, while tissue that produces fat and bone is called stromal and is yellow.
Marrow is able to generate new cells because it contains somatic stem cells, which can turn into any kind of cell, states the Genetic Science Learning Center of Utah. This allows marrow to regenerate, producing new marrow that can eliminate diseases. To treat leukemia, a cancer of white blood cells called leukocytes, doctors sometimes kill off a patient's diseased marrow and replace it with healthy marrow from a donor. The new marrow expands throughout the patient's body and produces healthy leukocytes.
Red marrow produces all red blood cells, most white blood cells, and platelets, states Medscape. The only major blood cell type that are not produced in the marrow are T lymphocytes, a special kind of white blood cell that stem cells produce in the lymph tissue. Yellow marrow mostly serves to store fat and to generate new fat, cartilage or bone. It also stimulates blood production.
Although the two kinds of tissue are distinct, they can convert from one to the other, states Medscape All marrow in newborns is red, but it slowly converts to yellow marrow as a consequence of aging. Yellow marrow can convert back to red marrow when large amounts of blood are lost. In old age, more and more red marrow is converted to yellow, hindering blood production.