3% Acetic Acid + Methylene Blue, 100mL

This 100 mL bottle from STEMCELL Technologies contains a 3% acetic acid solution supplemented with methylene blue, formulated as a simple, cost-effective reagent for lysing erythrocytes in single-cell suspensions prepared from peripheral blood, bone marrow, or dissociated spleen tissue. When a small aliquot of a cell suspension is mixed with the reagent, the acetic acid rapidly ruptures red blood cell membranes while leaving leukocytes and other nucleated cells intact; the methylene blue counterstain then lightly labels the exposed nuclei, making them easy to visualize and count on a hemocytometer under standard brightfield microscopy. It is a routine fixture in mouse immunology workflows, including downstream flow cytometry sample preparation and colony-forming unit assays, and it can also be used as a viability exclusion check because intact nuclei from dead cells remain visible alongside viable mononuclear cells. The reagent is supplied ready to use at room temperature in a 100 mL bottle and is stable for routine benchtop handling when stored away from direct light. Researchers commonly add 10 to 20 µL of sample to 180 to 200 µL of the solution, depending on expected cell density, before loading onto a counting chamber for an absolute nucleated cell count.