Background:

Trypan red is a vital stain.

[1]. POSCHEL PH. An effect of the vital dye trypan red on approach-avoidance conflict. J Comp Physiol Psychol. 1958 Aug;51(4):448-51. [2]. HURST EW, et al. The prevention of encephalitis due to the viruses of eastern equine encephalomyelitis and louping-ill: experiments with trypan red, mepacrine, and many other substances. Br J Pharmacol Chemother. 1952 Sep;7(3):455-72.