A counterstain, safranin is applied, which stains the colorless gram-negative cells. the appearance of gram positive cells is unchanged because the primary stain, crystal violet, is a much more intense stain than safranin.
Periodic acid-Schiff (PAS) is a staining method used in histology and pathology. This method is primarily used to identify glycogen in tissues. The reaction of periodic acid selectively oxidizes the...