Extramedullary hematopoiesis
![Micrograph showing nucleated red blood cells (bottom left of image), one of the elements necessary to call extramedullary hematopoiesis, in an endometrial polyp. H&E stain.](/Images/godic/202501/12/Nucleated_red_blood_cells_-_endometrial_polyp_-_high_mag3435.jpg")
Extramedullary hematopoiesis refers to hematopoiesis occurring outside of the medulla of the bone.
In some cases, it may be physiologic. For example, during fetal development, hematopoiesis occurs at many different locations, such as the liver and spleen.