What's new in light and electron microscopic immunocytochemistry? Application of the protein A-gold technique to routinely processed tissue.

The protein A-gold technique, a simple and reliable two-step postembedding immunocytochemical method, allows the light and electron microscopic detection of antigens in routinely fixed and embedded tissue. At the light microscopic level a permanent, nonfading stain is obtained. High resolution studies on intracellular antigens can be performed since the particulate nature of the colloidal gold permits accurate determination of the labeled cellular structures. The applicability of the protein A-gold technique for the localization of various peptide and protein antigens by light and electron microscopy is demonstrated.