Antibodies from an Rh negative mother may enter the blood stream of her unborn Rh positive infant, damaging the red blood cells (RBCs). The infant responds by increasing RBC production and sending out immature RBCs that still have nuclei. This photograph shows normal RBCs, damaged RBCs, and immature RBCs that still contain nuclei.
Update Date 11/19/2015
Updated by: Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.