The primary antibody specific to an antigen on formalin-fixed paraffin-embedded (FFPE) tissue section is detected by the Zeta Universal HRP Polymer Detection Kit. The antigen sites are then visualized with DAB chromogen/substrate. The reagent is ready-to-use in a convenient dropper bottle. The Zeta Universal HRP Polymer Detection Kit is a one-step system which uses a direct method resulting in a polymer-secondary antibodies-HRP complex that universally detects primary mouse and rabbit antibodies. The resulting chromogenic reaction can be visualized by HRP-compatible chromogens using light microscopy. The staining signals can be amplified with enhancer if necessary.