Information: Brilliant Cresyl Blue (1.5% in 0.85% Saline) is a supravital hematology stain for counting reticulocytes in peripheral blood smears. The number of reticulocytes in the blood is a simple measure of erythropoietic performance. Reticulocytes are immature erythrocytes that contain nuclear remnants of basophilic ribonucleoproteins which decreases as the reticulocyte matures. When stained, reticulocytes appear to contain dark blue granules or filaments. Reticulocytes: Blue/Green with Dark Blue Granules. Erythrocytes: Blue/Green Leukocytes: Light Blue