Which statement best describes the location of hematopoietic activity in adults?

Which statement best describes the location of hematopoietic activity in adults?

• A. In the bone marrow.
• B. In the brain.
• C. In the spleen.
• D. In the liver.

Answer: (A)

Hematopoietic activity in adults is located primarily in the bone marrow. The red marrow inside bones, especially in the axial skeleton and the proximal ends of long bones, remains active and continuously produces blood cells—red cells, white cells, and platelets. As people age, some marrow converts to fatty yellow marrow, but the sites that continue to generate blood cells stay within the bone marrow. The liver and spleen are important for hematopoiesis during fetal development and can take on hematopoietic roles again only in certain disease states (extramedullary hematopoiesis). The brain does not form blood cells. So the adult site of hematopoietic activity is the bone marrow.

Hematopoietic activity in adults is located primarily in the bone marrow. The red marrow inside bones, especially in the axial skeleton and the proximal ends of long bones, remains active and continuously produces blood cells—red cells, white cells, and platelets. As people age, some marrow converts to fatty yellow marrow, but the sites that continue to generate blood cells stay within the bone marrow. The liver and spleen are important for hematopoiesis during fetal development and can take on hematopoietic roles again only in certain disease states (extramedullary hematopoiesis). The brain does not form blood cells. So the adult site of hematopoietic activity is the bone marrow.