Bone marrow is the soft, fatty, vascular tissue that fills the cavities in large bones and and contains hematopoietic stem cells, from which develop erythrocytes (red blood cells), many leukocytes (white blood cells), and platelets. It is red or yellow in color. In new born babies, red bone marrow is present in all bones; during teen years, most is replaced by yellow marrow. The marrow used in bone marrow transplantation is red.

 

The bone marrow also contains mesenchymal stem cells that a number of cell types come from, including chondrocytes, which produce cartilage.

 

The sites of red bone marrow in adults: spine, sternum, pelvis, ribs, scapulae, clavicles, and skull bones.