e Development of Hematopoietic Organs Hematopoiesis after birth Bone marrow hematopoiesis All blood cells are produced in the marrow after 2nd trimester Newborn and early infancy: red marrow 5-7yr: yellow marrow Extrmedullary hematopoiesisDevelopment of Hematopoietic Organs • Hematopoiesis after birth – Bone marrow hematopoiesis • All blood cells are produced in the marrow after 2nd trimester • Newborn and early infancy: red marrow • 5-7yr : yellow marrow – Extrmedullary hematopoiesis