ARS | Publication request: A Simple Technique to Minimize Heat Damage to Specimens During Thermal Polymerization of LR White in Plastic and Gelatin Capsules

Submitted to: Journal of Microscopy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 22, 2008
Publication Date: July 15, 2008
Citation: Bowling, A.J., Vaughn, K.C. 2008. A simple technique to minimize heat damage to specimens during thermal polymerization of LR white in plastic and gelatin capsules. Journal of Microscopy, Vol. 231, Pt 1, pp. 186-189.

Interpretive Summary: Polymerization of plastic resins for microscopy, especially those required for processes involving subsequent antibody work, is often difficult. Workers at the Southern Weed Science Research Unit, Stoneville MS discovered a simple method to overcome these problems. A simple piece of dental wax is floated on the surface of the resin in the usual capsules used for electron microscopy. The wax melts as the plastic heats up during polymerization and the melted wax excludes oxygen that inhibits polymerization. Using this procedure, plastic could be polymerized in less than two hours, compared to the 24-48h recommended by the manufacturers, greatly improving the reaction of the specimen with antibodies.

Technical Abstract: LR White is a commonly used resin for embedding specimens to be used for immuno- and/or cytochemical studies. In some instances, due either to the properties of the specimen or to the availability of various reagents and equipment, it becomes necessary and/or more convenient to polymerize LR White using heat rather than chemical accelerators or UV light. It is known, however, that heat can reduce or even eliminate the antigenicity of the tissue being embedded. It is therefore desirable to polymerize specimens at the lowest temperature possible and to remove the specimens from the oven as soon as polymerization is complete. We have developed a technique that provides a visual marker which allows the exothermic polymerization of LR White to be monitored, thus minimizing the amount of time a specimen must stay in the oven, while at the same time excluding oxygen from capsules of polymerizing LR White.