Hematopoietic system

the blood-making organs

Description
The makeup of the hematopoietic system is developmentally regulated. In the embryo at different ages hematopoietic organs are yolk sac, liver, thymus, spleen, lymph nodes, and bone marrow; after birth they are the bone marrow of the sternum and iliac bone, the thymus and the lymph nodes. Anemic conditions, such as those brought about by hemoglobinopathies, can lead to medullary (i.e. bone-marrow-derived) and extramedullary expansion of hematopoietic tissues.