Principle of Masson Fontana Stain
The principle behind the Masson Fontana stain is based on the ability of argentaffin substances to reduce silver nitrate to metallic silver, which then appears as black deposits under the microscope. This method involves treating tissue sections with a silver nitrate solution, followed by a reducing agent if necessary, to visualize these substances.Applications of Masson Fontana Stain
The Masson Fontana stain is widely used in the field of
histopathology for several applications:
Procedure of Masson Fontana Stain
The staining procedure typically involves the following steps: Fix tissue sections in an appropriate fixative, usually
formalin.
Deparaffinize and rehydrate the sections through a series of alcohol washes.
Immerse the sections in a
silver nitrate solution for a specified duration.
Rinse the sections and apply a reducing agent if necessary. In some protocols, the tissue's inherent reducing properties are sufficient.
Wash the sections, dehydrate, clear, and mount them for microscopic examination.
Interpretation of Results
Under the microscope, tissues stained with the Masson Fontana method show black to dark brown deposits where argentaffin substances are present. For example,
melanin granules will appear black, aiding in the diagnosis of melanocytic lesions and other pigment-related conditions. Similarly, argentaffin granules in neuroendocrine cells will also appear black, assisting in identifying
neuroendocrine tumors.
Advantages and Limitations
The Masson Fontana stain has several advantages: High specificity for argentaffin substances like melanin.
Relatively simple and cost-effective procedure.
Provides clear contrast, making it easier to identify target structures.
However, there are also some limitations:
Potential for non-specific staining if the procedure is not carefully controlled.
Some substances may require additional reducing agents for effective visualization.
Not suitable for all types of tissue or substances.
Conclusion
Overall, the Masson Fontana stain is a valuable tool in histology for identifying and studying
argentaffin substances, particularly melanin and neuroendocrine granules. Its specificity and simplicity make it a widely used technique in both research and clinical diagnostics.
