Is the specific localisation of cell and extracellular matrix components using the interactions between antigens and their respective antibodies.

To enable visualisation, antibodies are labelled either directly or indirectly using a fluorescent dye or an enzyme-substrate complex.

Further amplification of the signal is also possible using indirect methods if there is minimal antigen present in the tissue.

Alpha Smooth Muscle Actin labelling of an artery wall

Von Willebrand factor (VWF) staining of blood vessels in a tonsil section