The lipid solubility of fixative, staining and embedding media, and the introduction of LX-112 and poly/bed-812 as dehydrants for epoxy resin embedment.

The manufacture of Shell, Epon-812 (E-812) resin has recently been discontinued. E-812 and two newly introduced E-812 substitutes, and Ladd-112 (LX-112) and the Polysciences, Poly/bed-812 (PB-812) resins, were studied biochemically and morphologically for their effectiveness as polar dehydrants. Their technical properties as general E-812 replacements were also explored. In the biochemical studies, acetone was more effective in retaining lung phospholipid components than ethanol, the resin dehydration was more effective than either acetone or ethanol. There was no appreciable difference in lipid solubility among the three resins. Acetone and uranyl magnesium acetate each had a loosening effect on previously fixed phospholipids. The PB-812 and E-812 resin dehydrated blocks of dense animal tissues, demonstrated serious technical difficulties during sectioning. The L-112 resin substitute, due to its low viscosity and improved infiltration, was found to be technically as effective a dehydrant as ethanol or acetone. None of the three resins was successful as dehydrating agents for the plant tissue. With organic solvent dehydration, both epoxy resin substitutes demonstrated excellent embedment properties with both animal and plant tissues.