Enzyme histochemical demonstration of NADH dehydrogenase on resin-embedded tissue

We describe a method for enzyme histochemical demonstration of NADH dehydrogenase in cold (4 degrees C)-processed resin-embedded tissue. The effects on NADH dehydrogenase activity of processing tissue through a variety of dehydrating agents and embedding in three different acrylic resins were evaluated. The optimal procedure to maintain NADH dehydrogenase activity used a short (3-hr) fixation in 1% paraformaldehyde solution, followed by dehydration in acetone and embedding in glycol methacrylate resin. Embedding of tissue in resin combined preservation and accurate localization of NADH dehydrogenase activity with good tissue morphology. Blocks of the resin-embedded tissue could be stored at room temperature for at least 6 months without loss of NADH dehydrogenase activity.