Antigen detection on resin sections and methods for improving the immunogold labeling by manipulating the resin

Considering the importance of immunolocalization of cellular substances combined with good ultrastructure and ease of use, this review is focused on the use of resin and the possibilities of manipulating the resin before and after embedding in order to improve the immunolabeling of resin sections for electron microscopy. The qualities of acrylic resins and conventional epoxy resin for immunoelectron microscopy are discussed. Acrylic sections are usually more suited for immunoelectron microscopy than conventional epoxy sections. Different etching procedures (sodium ethoxide or sodium metaperiodate) may be applied to conventional epoxy sections to enhance the yield of immunolabeling. Lately, a method which does not involve any kind of etching has been developed for enhancing the immunogold labeling of epoxy sections up to about 8 times. This method involves increased concentration of accelerator in the epoxy resin mixture when processing the tissue. The ultrastructural preservation of the tissue is important in immunoelectron microscopical procedures, and not only the intensity of the immunolabeling; in this respect no resin may compete with the widely used epoxy resins.