What is the purpose of an endospore stain?

• A. To stain Gram-positive cell walls purple.
• B. To visualize dormant endospores.
• C. To observe flagella.
• D. To identify capsules.

Answer: (B)

Endospore staining is used to visualize dormant endospores inside bacteria. These structures form a tough, resistant coat that hiding inside a cell makes them difficult to see with ordinary stains. By applying heat with a dye like malachite green, the stain penetrates the spore coat and remains trapped in the endospore. After a rinse, the surrounding vegetative cell is decolorized and then counterstained (often with safranin), so the endospore stands out—typically green—while the rest of the cell is pink/red. This technique specifically reveals the presence of endospores, not the overall Gram reaction, flagella, or capsules, which require different staining methods.