toluidine blue O

[tō-lōōĭ-dēn′, -dĭn, tə-]
n.
  1. A blue basic dye used as a heparin antagonist, an antibacterial agent, a nuclear and metachromatic stain, and a stain for electrophoretic analysis of RNA, RNase, and mucopolysaccharides.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.