A counterstain is a stain with colour contrasting to the principal stain, making the stained structure easily visible using a

microscope A microscope () is a laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisibl ...

. Examples include the malachite green counterstain to the fuchsine stain in the Gimenez staining technique and the eosin counterstain to haematoxylin in the

H&E stain Hematoxylin and eosin stain ( or haematoxylin and eosin stain or hematoxylin-eosin stain; often abbreviated as H&E stain or HE stain) is one of the principal tissue stains used in histology. It is the most widely used stain in medical diagnos ...

. In Gram staining, crystal violet stains only

Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bac ...

bacteria, and safranin counterstain is applied which stains all cells, allowing the identification of Gram-negative bacteria as well. An alternative method uses dilute carbofluozide. Counterstains are sometimes used to separate animals from organic

detritus In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts commu ...

in microbiology studies.

References

Staining {{pathology-stub