Use of immunogold with silver enhancement.

Although gold particles are readily detectable by transmission electron microscopy, they can be difficult to visualize by bright-field light microscopy. However when the gold is silver-enhanced it is easy to see. During silver-enhancement, the colloidal gold serves as a nucleation site for the deposition of metallic silver. The enhancing solutions are physical developers that contain both silver ions and a reducing agent, buffered to an acid pH. The silver-enhancement method has also been used successfully to enlarge small-diameter gold particles for visualization by scanning electron microscopy. Silver-enhancement has been applied to a wide variety of tissues and antigens for both light and scanning electron microscopy.