DER 332-732

Introduction

This kit combines two epoxy resins, DER 332, a very pure and uniform epoxy having a low viscosity, and DER 732, a polyglycol diepoxide which imparts softness and flexibility to the polymers of conven-tional epoxides, but does not cause shrinkage or serious loss of strength. Together with their curing agents, this kit produces a standard amber-colored block which can be trimmed and sectioned easily.

Recommended Procedure

Fixation: Tissues can be fixed in a wide range of fixatives. One of the more commonly used fixatives is an alde-hyde (i.e.: glutaraldehyde) followed by osmium tetroxide.

Dehydration: There are many different dehydration schedules that can be followed. A typical one is as follows:

• 70% Ethanol for 10 minutes
• 100% Ethanol for 10 minutes100% Ethanol for 15 minutes
• 100% Propylene Oxide for 15 minutes
• 100% Propylene Oxide for 15 minutes

**NOTE: Longer times may be required for some samples.

Mixing Instructions:

(FOR LARGER BATCHES INCREASE EACH COMPONENT PROPORTIONALLY)

Slight variations of the accelerator (DMP-30) will drastically affect the color and brittleness of the block.

Prior to measuring and mixing, the resin and the anhydride should be warmed (60°C) to reduce their viscosity. Thorough mixing is imperative to be able to achieve uniform blocks.

Although the mixture can be stored for up to 6 months at 4°C it is highly recommended that freshly prepared embedding medium always be used. If you choose to store the mixture you should warm it thoroughly prior to adding the accelerator.

Infiltration:It is recommended that for all of the infiltration steps a specimen rotator be used.

• Drain the tissue of most of the propylene oxide, leaving a little so the tissue does not dry out.
• Replace the solvent with a 1:1 solution of propylene oxide:embedding medium and allow it to stand for at least 1 hour at room temperature.
• Remove the mixture, replace it with 100% embedding medium and leave for 6-12 hours at room temperature.

Embedding:This may be done in embedding capsules #E70020 or a flat embedding mold #E70900).

Transfer each sample to a dry capsule or mold and fill the mold with embedding medium. Curing of the medium may be carried out in an oven at 37°C, 45°C, and 60°C for 24 hours at each temperature.

Blocks can be trimmed and sectioned after the blocks return to room temperature.

*This formula was suggested by Bluemink(1970) in accordance with the recommendations of Coulter(1967) concerning anhydride/epoxy ratios.

References
Lockwood, W.R.(1964), Anatomical Record, 150, 129.Bluemink, J.G.(1970), J. Ultrastruct. Res. 32, 142.