Stains In Focus: The History of May Grunwald Giemsa

The May-Grünwald-Giemsa (MGG) stain is a Romanowsky-type staining method used for the examination of blood smears, bone marrow aspirates and cytological preparations. By combining May-Grünwald and Giemsa staining techniques, it provides clear differentiation of cellular components for detailed morphology assessment.

The interaction between eosin and oxidised methylene blue derivatives produces a characteristic range of colours, allowing nuclei, cytoplasm and intracellular structures to be distinguished clearly. This makes MGG a well-established method in haematology and cytology workflows.

The Development of MGG Staining

The MGG stain developed from earlier Romanowsky methods and became established as a sequential staining approach that improves consistency and cellular detail.

May-Grünwald Stain

The May-Grünwald stain is based on a Romanowsky-type formulation containing eosin and methylene blue in methanol, allowing fixation and initial staining to occur in the same step. This provides early differentiation of cellular components and prepares the specimen for further staining with Giemsa.

Combined MGG Technique

The combination of May-Grünwald and Giemsa staining steps creates a sequential method that supports clarity and consistency. The May-Grünwald step fixes and partially stains the cells, while the Giemsa step enhances nuclear detail and cytoplasmic contrast, resulting in a balanced and reproducible stain.

Staining Mechanism

The MGG stain relies on the interaction between acidic and basic dye components. Eosin, an acidic dye, stains basic cellular structures such as cytoplasmic proteins in shades of pink. Azure B and other oxidised methylene blue derivatives bind to nucleic acids, producing blue to purple nuclear staining.

This interaction creates the characteristic Romanowsky effect, allowing visual separation of cell types and internal structures.

Applications of MGG Staining

Haematology: MGG staining is routinely used for peripheral blood films and bone marrow examination. It supports the identification and differentiation of leucocytes, erythrocytes and platelets, as well as the detection of abnormal cell morphology.

Cytology: In cytological preparations, MGG provides clear nuclear and cytoplasmic detail, supporting diagnostic evaluation of fine needle aspirates and body fluids.

Parasitology: Related Romanowsky stains, particularly Giemsa, are widely used for detecting blood parasites, including malaria, where clear visualisation of intracellular structures is required.

Advantages of MGG Staining

The sequential staining approach supports reproducible results and provides consistent contrast across a range of sample types. The use of methanol in the May-Grünwald step also supports a practical and efficient laboratory workflow.

MGG is compatible with routine laboratory practice, making it suitable for diagnostic and research environments.

Atom Scientific’s Romanowsky Stains

Atom Scientific manufactures IVDR-registered, ISO 13485-compliant stains and stain kits in the UK. Our Romanowsky stain range is designed to support diagnostic laboratories with pre-validated products, batch traceability and documented protocols.

Our ready-to-use stain kits support routine laboratory workflows by helping reduce preparation time and maintain consistent staining performance. Each kit is manufactured with batch and raw material traceability, supporting a clear audit trail when required.

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Supporting Diagnostic and Research Workflows

The May-Grünwald-Giemsa stain remains a widely adopted method for cellular analysis due to its ability to provide clear, differential staining across multiple applications. Its development from earlier Romanowsky techniques has resulted in a reproducible approach that continues to support diagnostic and research workflows.

MGG Atom Stain Kit