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A stain of a contrasting color used to color the components in a microscopic specimen that are not made visible by the principal stain.
tr.v. coun·ter·stained, coun·ter·stain·ing, coun·ter·stains
To color (a microscopic specimen) with such a stain.
1. (Biology) to apply two or more stains in sequence to (a specimen to be examined), each of which colours a different tissue
2. (Biology) (tr; usually passive) to apply (one of a series of stains) to a specimen to be examined: haematoxylin is counterstained with eosin.
1. a second stain applied to a microscopic specimen for contrast.v.t.
2. to treat (a microscopic specimen) with a counterstain.v.i.
3. to become counterstained; take a counterstain.
Past participle: counterstained