A fixation step is, of course, not necessary for materials samples.
Dehydration for GMA embedments does not have to be complete because
of GMA's miscibility in water. Only if the sample is saturated
with water should a schedule of increasing alcohol concentration
be used. This will displace most of the water with a solvent that
can be replaced with plastic. Use schedule as follows:
- 70% ethanol for 10 minutes.
- 96% ethanol for 10 minutes.
- 96% ethanol for 10 minutes.
- absolute ethanol for 10 minutes.
Infiltration displaces the
dehydration solvent with monomer prior to beginning the polymerization
reaction.
If you have a porous
sample, infiltration may be needed. Nonporous samples can skip
this step. Make up your infiltrating solution according to the
directions from your kit. For reusable Teflon� molds for more effective
heat removal are available from DDK. While complete elimination
of air is not needed, sealing the molds with paraffin or plastic
wrap is often done. Leave the samples at room temperature for 1
hour then at 37� C for one hour to complete polymerization.
If your embedments cannot be mounted directly
to the microtome, an adapter must be attached. Place the suitable
Technovit
3040 is an inexpensive media prepared by mixing 3 parts of
the dry component to 1 part of the liquid component. Pour it into
the adapter and polymerization will be complete within 10 minutes.
The adapters will be firmly attached through a copolymerization
of the Technovit 3040 with the GMA.
You are now ready to begin sectioning with
glass.
