Glycol methacrylate (GMA) resins, such as Immuno-Bed and JB-4, allow for tissue preservation and morphological differentiation that is superior to that seen with paraffin embedding or frozen sections. Sections can be routinely cut at 1-3um thickness, depending on the size and texture of the sample. Thinner sections are particularly useful when observing and counting small features that may be stacked on top of each other in a 5-6um paraffin section.

Unlike paraffin embedding, heating of the specimen is not necessary. All steps in the processing can be performed at or below room temperature, and the final polymerization, which is exothermic, is performed at 20° C. This is of cirtical importance for the immunological staining of heat-labile antigens.

Unlike most resins used for electron microscopy, Immuno-Bed resin is hydrophilic, and allows large immunoglobulin molecules through the section for demonstration of antigenic sites. A wide variety of staining and histological techniques for light microscopy can also be used. Immuno-Bed resin has been specially formulated for immunological work, and techniques have been successfully developed for locating many antigens. Protocols that have been developed for paraffin embedded sections, however, may need modification to work with Immuno-Bed.

GMA embedded specimens are cut with glass knives that are 12mm wide. The practical width of the specimens that can be cut, therefore, is about 11mm. Specimen length can be up to about 20mm.

Immuno-Bed and JB-4 embedding is more expensive than paraffin, and may not be cost effective for many studies. They should be considered for studies where thinner sections are necessary, or where the harder embedding matrix is useful to improve sectioning. Immuno-Bed is particularly useful when antigens are destroyed or extracted during paraffin embedding. Because it is possible to use GMA instead of ethanol as a dehydrating agent, in some cases materials that are extracted with ethanol may be preserved.

Immuno-Bed and JB-4 resins are used for light microscopy only.