In this technique, heating acts as a mordant. When a heat-fixed smear is flooded with aqueous malachite green solution (the primary stain) and steamed, the heat assists the stain in penetrating through the spore. The method utilizes malachite green as the primary stain and safranin as a counterstain. Schaeffer and MacDonald Fulton in the 1930s.
The technique was first described by Alice B. It is the most widely used technique for endospore staining. They appear as large refractile oval or spherical bodies within the mother cell. Endospores can also be demonstrated in unstained wet films under a phase-contrast microscope. Spores can generally be recognized on Gram’s stains (endospores do not stain and appear as refractile, nonstaining bodies).
There are different methods for endospore staining. Other techniques of endospore staining Methods for endospore staining.Principle of Dorner’s method for staining endospores.