Physio 1

7. Before birth, hemopoiesis first occurs in the yolk sac of an embryo and later in the liver,spleen,thymus and lymph nodes of a fetus. Red bone marrow becomes the primary site of haemopoiesis in the last 3 months before birth and continues as the source of blood cells after birth and throughout life. However,maturation , activation and some proliferation of lymphoid cells occurs in secondary lymphoid organs (spleen, thymus,and lymph nodes). In children, haematopoiesis occurs in the marrow of the long bones such as the femur and tibia. In adults, it occurs mainly in the pelvis, cranium, vertebrae, and sternum. LOCATION OF HAEMATOPOIESIS

18. HAEMATOPOIESIS – RBCs