C3O1U1N1T1E1R1S1T1A1I1N1S1
15 points
COUNTERSTAINS is validvalid
COUNTERSTAIN, [v]
COUNTERSTAIN, to apply additional dye to a specimen to produce a contrasting background [v]
COUNTERSTAIN, [v]
COUNTERSTAIN, to apply additional dye to a specimen to produce a contrasting background [v]