MayGrunwaldGiemsa

May-Grünwald-Giemsa is a polychromatic Romanowsky-type stain used to color cells in thin smears, most commonly peripheral blood smears, bone marrow aspirates, and various cytology preparations. It combines two sequential staining steps—the May-Grünwald stain followed by the Giemsa stain—to produce a broad spectrum of colors that differentiate cellular and nuclear features.

The stain is based on a mixture of methylene blue, azure dyes, and eosin in methanol and buffered solutions. The May-Grünwald step provides initial cytoplasmic and nuclear staining, while the subsequent Giemsa step, performed in a buffered medium, enhances contrast and detail. The result is a stained preparation in which cell types exhibit characteristic hues: nuclei appear blue to purple, cytoplasm ranges from pale blue to pink, and granules or parasites may show more distinct colors. The technique is particularly valued for clearly highlighting leukocyte differential features, platelets, and intraerythrocytic or tissue parasites.

Procedure is typically performed on fixed slides: fixation in methanol, brief staining with May-Grünwald solution, followed by immersion in a buffered Giemsa solution. Staining times and buffer pH are important for reproducibility. Variants include different ratios and commercial pre-mixed preparations, and the method can be adapted for automated stainers.

Applications include hematology for differential leukocyte counts and bone marrow assessment, parasitology for detecting malaria and other blood-borne organisms, and cytology for general cellular morphology. Safety considerations involve handling methanol and chemical stains in a well-ventilated area with appropriate disposal.