Used in histopathology and virology to detect viral inclusion bodies in tissue sections. The stain helps differentiate infected cells by clearly visualizing intranuclear or cytoplasmic inclusion bodies under a light microscope. Methylene blue stains the nucleus and inclusion bodies in varying shades of blue, while eosin highlights cytoplasmic details in pink to red tones, providing contrast. This method is particularly useful in diagnosing viral infections such as herpes simplex, rabies, or cytomegalovirus in clinical samples. It is a simple, cost-effective staining technique for routine diagnostic pathology and research settings where rapid identification of viral cytopathic effects is needed.