Procure-Araldite Embedding Kit

Introduction:
The combination of different embedding resins is popular because these kits blend the best qualities of each individual resin into one.

In 1964, Mollenhauer developed an Araldite-Epon (PROCURE-812) mixture for embedding plant tissue, with particular interest in preserving the plant cell wall. It has also shown to be successful with animal tissue. Sectioning with this mixture of resins has proven to be easier than with the individual resins and the thermal stability of Araldite and the image contrast of PROCURE has made this a very successful blend.

Recommended Procedure:

Fixation:

Tissues can be fixed in a wide range of fixatives. One of the more commonly used fixatives is an aldehyde (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 minutes
100% 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 better penetration and stability BDMA is recommended in place of the DMP-30.
The quantity of BDMA which is required is 2.4-2.8ml.

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

(FOR LARGER BATCHES INCREASE EACH COMPONENT PROPORTIONALLY)

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 4ºC 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.

1. Drain the tissue of most of the propylene oxide, leaving a little so the tissue does not dry out.
2. 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.
3. Remove the mixture, replace it with 100% embedding medium and leave for 6-12 hours at room temperature.
4. Replace the old mixture with fresh embedding medium and allow it to sit for at least 2 hours.

Embedding:

This may be done in embedding capsules or a flat embedding mould.

Transfer each sample to a dry capsule or mould and fill the mould with embedding medium. Cure the medium in an oven at 60ºC for 12 hours or until it is hard. Better sectioning properties of certain samples may be achieved if a time of 24 hours in the oven is used.

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

REFERENCES:

Mollenhauer, H.H. (1964), Stain Technology, 39, 111.