There are a few physiologic points a medical laboratory professional should keep in mind regarding blood cell formation, development, and differentiation known as hematopoiesis.
Changing sites of hematopoiesis:
- At the third week of pregnancy, hematopoiesis has started in the fetal yolk sac.
- The fetal liver takes over this role around the second month of fetal development.
- By six months of fetal development, the bone marrow has taken over the responsibility of hematopoiesis.
- In a newborn, all sites of bone marrow in the body contribute to hematopoiesis, especially the long bones of the legs.
- Over time, the hematopoietic bone marrow of the long bones becomes replaced with fat. The sternum (breastbone), vertebrae, ribs, and pelvis become the remaining locations of hematopoietic bone marrow in the body. These locations remain the predominant sites of hematopoiesis throughout the remainder of adult life.
