This digitally-colorized scanning electron micrograph (SEM) revealed some of the comparative ultrastructural morphology between normal red blood cells (RBCs), and a sickle cell RBC (left) found in a blood specimen of an 18 year old female patient with sickle cell anemia, (HbSS). People who have this form of sickle cell disease inherit two sickle cell genes (?S?), one from each parent. This is commonly called ?sickle cell anemia?, and is usually the most severe form of the disease. Sickle cell di