Final answer:
Hematopoiesis after 2 months of conception primarily occurs in the red bone marrow, which includes the pelvis, ribs, sternum, vertebrae, and the ends of long bones.
Step-by-step explanation:
Hematopoiesis is the process of blood cell production, which continues throughout an individual's life due to the short lifespan of most blood cells. After conception, initially the yolk sac takes on the role of hematopoiesis. As the embryo develops, this responsibility sequentially shifts to the fetal liver, spleen, and lymphatic tissues.
Post birth, the primary site for hematopoiesis becomes the red bone marrow, which is found in spaces within spongy bone. In children, hematopoiesis also occurs in the medullary cavities of long bones, whereas in adults, it is concentrated in the pelvis, ribs, sternum, vertebrae, and the ends of long bones such as the femur and humerus.
Red bone marrow is crucial as it produces essential cellular components of blood including erythrocytes (red blood cells), several types of leukocytes (white blood cells), and platelets. The B lymphocytes mature almost entirely within the red marrow, while T lymphocytes, known as thymocytes.