Final answer:
Leishman stain is preferred over methylene blue or crystal violet because it provides better visualization and differentiation of cell components. Leishman stain is a combination of basic and acidic dyes, which aids in visualizing different types of cells and structures. It is specifically designed for studying blood cells and parasites.
Step-by-step explanation:
Leishman stain is used because it provides better visualization of certain cell components, such as the nucleus and cytoplasm. Methylene blue and crystal violet are basic stains, whereas Leishman stain is a combination of basic and acidic dyes. The acidic component of the Leishman stain helps to differentiate different types of cells and structures within the specimen. Additionally, Leishman stain is specifically designed for use in studying blood cells and parasites, making it more suitable for certain applications compared to methylene blue or crystal violet.