The buffy coat above the volume of concentrated red blood contains white blood cells and platelets. Plasma represents the largest percentage of total blood volume. The kidney produces erythropoietin hormones which stimulate the production of red blood cells in the red bone marrow, known as the process of erythropoiesis (Mader, 2010). Erythrocytes (red blood cells) are mainly used to transport oxygen and carbon dioxide for gas exchange. Red blood cells lack a nucleus. They contain hemoglobin which mainly binds to oxygen to transport it to the tissues. Red blood cells have an average lifespan of 120 days and are destructive to the spleen and liver. Degraded hemoglobin, iron and bilirubin are recycled. Nutrients such as vitamin B12, folic acid and iron are necessary for erythropoiesis. Leukocytes or white blood cells have a granular or a-granular nucleus (Mader, 2010). Leukocytes are translucent and observed by staining. The granular leukocytes are neutrophils, basophils and eosinophils. Neutrophils are neutral or dye-free in color and have a nucleus of more than 3 lobes (Sherwood, 2012). Eosinophils have the affinity for the red dye, eosin, and basophils have the blue dye..