Which marrow type is adipose tissue?

• A. Red marrow stores fat
• B. Red marrow hematopoietic tissue
• C. Yellow marrow hematopoietic tissue
• D. Yellow marrow adipose tissue

Answer: (D)

Yellow marrow is adipose tissue. In adult bones, fat cells accumulate in the medullary cavity to form yellow marrow, which mainly stores fat and serves as an energy reserve rather than producing blood cells. Red marrow, by contrast, is hematopoietic tissue responsible for making red blood cells, white blood cells, and platelets. While yellow marrow can sometimes revert to red marrow if the body needs more blood cells, its normal state is adipose-dominant. So the marrow type that is adipose tissue is yellow marrow.