During supravital staining, non-fixed cells are stained. The staining solution is added to whole blood. This mixture is incubated, and then the blood film is prepared. This stains cell components which can no longer be stained after fixation. Typically used stains include: Brilliant cresyl blue, new methylene blue or crystal violet.
Residual RNA in reticulocytes and denatured hemoglobin (Heinz bodies) are stained blue.
Reticulocyte counting and demonstration of Heinz bodies. A modified supravital stain is used to demonstrate red cell inclusions in HbH disease.