Life Sciences Commons^™

Detection Of Small (5-15nm) Gold-Labelled Surface Antigens Using Backscattered Electrons, Paul Walther, Martin Müller

Scanning Electron Microscopy

The analysis of surface antigens by scanning electron microscopy represents a practicable alternative to replica techniques. It is generally observed that smaller markers provide for better labelling. In the SEM very small colloidal gold labels however are hardly discerned from contaminants or from surface structures of similar size. They are however unambiguously demonstrated by combining the surface information provided by the secondary electron signal and the material dependent signal provided by the backscattered electrons. A field emission SEM equipped with a highly sensitive single crystal backscattered electron detector allows the routine detection of 5 nm gold particles on biological surfaces. …

Immuno-Cytochemistry With Backscattered Electrons, D. Soligo, E. De Harven, M. T. Nava, G. Lambertenghi-Deliliers

Scanning Electron Microscopy

Some cytochemical reaction products are visible inside the cytoplasm of cells observed with the scanning electron microscope (SEM) using the backscattered electron imaging (BEI) mode. Methods can be utilized whenever they result in the deposition of heavy metal, like silver, lead or osmium at the sites of the enzymatic reaction.

More recently the BEI mode of the SEM has been demonstrated to improve the detection of immunogold labeled cell surface antigens. Colloidal gold particles, 40 to 15 nm in diameter can be efficiently used for immuno-specific labeling. Moreover, cytochemical reactions can be applied to previously immunogold labeled cells, therefore combining …

To Resin Or Not To Resin In Immunocytochemistry, J. J. Wolosewick

Scanning Electron Microscopy

Hydrated resinless sections produced by a variety of methods (cryoultramicrotomy or polyethylene glycol techniques) appear to be excellent specimens for post-embedding immunocytochemistry at the electron microscopic level. A perplexing problem is the lack of apparent penetration throuqhout the section thickness of particulate probes such as ferritin or colloidal gold. This report draws attention to the possible causes for this phenomenon namely the size of the probe and the possible effects of fixation or processing. Smaller probes, gentler fixation or permeabilization procedures and increased incubation times all seem to be logical approaches to increasing penetration of immunoreagents into thick hydrated sections.