A marked increase in the number of nucleated red blood cells (NRBCs) can be seen here . The orthochromatic erythroblasts lie in this region in particular. The larger NRBC population also suggests the presence of polychromatic erythroblasts. Erythroblastosis occurs with greatly increased erythropoiesis and is frequently seen in premature infants, in transfusion-dependent hemoglobinopathies and after substantial blood loss.

Below is a timeline of approximately 7 days showing massive increases in erythropoiesis after much blood loss associated with a ruptured abdominal aortic aneurysm (AAA).