What is the purpose of methylene blue in histopathologic examination?

Methylene blue is primarily utilized in histopathologic examination for its ability to stain specific cellular components, particularly in the identification of plasma cells. Plasma cells, which are derived from B-lymphocytes, are involved in the production of antibodies and can be critical in the evaluation of various conditions. Methylene blue effectively highlights these cells due to its affinity for the RNA present in their cytoplasm, allowing pathologists to visualize and assess their presence and abundance within a tissue sample.

The choice regarding staining glycogen, highlighting neuroglia, or diagnosing bacterial infections does not align with the main applications of methylene blue in histopathology. While methylene blue can have some general uses in microbiology for the observation of bacteria, its primary role in histopathology is focused on identifying plasma cells.