Which tissue is the primary site of hematopoiesis in adults?

Which tissue is the primary site of hematopoiesis in adults?

• A. Adipose tissue
• B. Areolar connective tissue
• C. Bone marrow
• D. Hyaline cartilage

Answer: (C)

Hematopoiesis in adults occurs primarily in bone marrow, where hematopoietic stem cells reside and differentiate into all blood cell lineages—red blood cells, various white blood cells, and platelets. In adults, the red marrow that actively produces blood cells remains mainly in the axial skeleton (like the skull, vertebrae, ribs, sternum) and the ends of long bones; much of it can convert to yellow marrow with fat, but the sites that still actively generate blood cells are bone marrow. Other tissues listed do not produce blood cells. Adipose tissue stores fat and energy, not blood; areolar connective tissue provides general support but isn’t a site of hematopoiesis; hyaline cartilage is avascular and specialized for cushioning, not blood cell formation.

Hematopoiesis in adults occurs primarily in bone marrow, where hematopoietic stem cells reside and differentiate into all blood cell lineages—red blood cells, various white blood cells, and platelets. In adults, the red marrow that actively produces blood cells remains mainly in the axial skeleton (like the skull, vertebrae, ribs, sternum) and the ends of long bones; much of it can convert to yellow marrow with fat, but the sites that still actively generate blood cells are bone marrow.

Other tissues listed do not produce blood cells. Adipose tissue stores fat and energy, not blood; areolar connective tissue provides general support but isn’t a site of hematopoiesis; hyaline cartilage is avascular and specialized for cushioning, not blood cell formation.