regressive staining

re·gres·sive stain·ing

a type of staining in which tissues are overstained and the excess dye is then removed selectively until the desired intensity is obtained.

re·gres·sive stain·ing

(rĕ-gres'iv stān'ing)
A type of staining in which tissues are overstained and the excess dye is then removed selectively until the desired intensity is obtained.