Negative Stain

∞ generated and posted on 2016.01.13 ∞

Means of viewing a specimen microscopically that involves increasing the contrast associated with the background rather than with the specimen.

Negative staining is used for viewing structures to which dye poorly adheres, such as bacterial capsules, i.e., as in capsule staining. Acidic dyes are used in negative staining since they tend to adhere to the background but not the negatively charged specimen (contrast basic dye). Commonly used acidic dyes include nigrosin, India ink, and Congo red. See, equivalently, indirect stain.

The following video provides an overview of a common means of negative staining, here using nigrosin as the acidic dye: