Sarıkemik iliği, or yellow bone marrow, is a type of bone marrow found in the cavities of long bones. It primarily consists of adipose tissue, which stores fat, and plays a role in energy storage. Unlike red bone marrow, which produces blood cells, yellow marrow is less active in hematopoiesis. In adults, sarıkemik iliği can replace red bone marrow in certain bones as a person ages. While it does not produce blood cells, it can convert back to red marrow if the body requires more blood cell production, such as during severe blood loss or anemia.