A vital stain in a casual usage may mean a stain that can be applied on living cells without killing them. Vital stains have been useful for diagnostic and surgical techniques in a variety of medical specialties. In supravital staining living cells that have been removed from an organism, whereas intravital staining is done by injecting or otherwise introducing the stain into the body. The term vital stain is used by some authors to refer to an intravital stain, and by others interchangeably with a supravital stain, the core concept being that the cell being examined is still alive. But in a more strict sense the term vital staining has a meaning contrasting with supravital staining. While in supravital staining the live cells take up the stain, in "vital staining" - the most accepted but apparently paradoxic meaning of this term, the live cells exclude the stain i.e. stain negatively and only the dead cells stain positively and thus viability can be assessed by counting the percentage of total cells that stain negatively. Very bulky or highly charged stains that don't cross live plasma membrane are used as vital stains and supravital stains are those that are either small or are pumped actively into live cells. Since supravital and intravital nature of the staining depends on the dye, a combination of supravital and vital dyes can also be used in a sophisticated way to better classify cells into distinct subsets (e.g. viable, dead, dying etc.).
Read more about Vital Stain: List of Common Vital Stains
Famous quotes containing the words vital and/or stain:
“In the first place, all books that get fairly into the vital air of the world were written by the successful class, by the affirming and advancing class, who utter what tens of thousands feel though they cannot say.”
—Ralph Waldo Emerson (1803–1882)
“Then suddenly the noon turns afternoon
And afternoon like an ill-written page
Will fade, until the very stain of light
Gathers in all the venom of the night
The equilibrium of the thirtieth age.”
—Allen Tate (1899–1979)