Howell-Jolly bodies are blue to violet, round,refractile inclusions in erythrocytes and are usually < 0.5 µm in diameter. They represent nuclear remnants. They are can be seen at the edge of the cell, and there is usually only one present. Howell-Jolly bodies are continuously removed by the spleen and cannot be found in the blood of healthy persons!
Howell-Jolly bodies occur with nuclear maturation defects (e.g. megaloblastic anemia), with accelerated erythropoiesis (e.g. hemolytic anemia) as well as after splenectomy or functional asplenia (e.g. after recurrent spleen infarctions or in neonates with immature spleen).