Use of Reichert - Jung Cryotome-1
These are commonly used in Hospitals
for quick tissue analysis. If you are on or near a major university, there is probably a
Cryotome there. The Cryotome consists of a Microtome for cutting thin sections
(5-60 microns) placed inside a freezer. The standard procedure for cutting thin sections
involves killing the tissue and preserving it, removing water with alcohol, infiltrating
it with wax or resin, polymerizing it, then sectioning it. This is tedious and frequently
changes the composition and appearance of the specimen so that it must be stained
artificially. The advantage of this procedure is that the sections can be very thin 1m and
permanent.
Fresh or preserved specimens can be cryosectioned with little preparation. The procedure is rapid and the natural colors of the specimen are retained. Sections can be stained with almost any type of chemical. However, the sections are usually much thicker (20 m), they are not permanent and not all materials can be used. Resilient specimens like leathery leaves, petioles and twigs can be sectioned. Extremely delicate or hard materials create problems which require some experimentation.
While fresh, untreated specimens can be frozen and sectioned, it is customary to infiltrate the tissue with an antifreeze solution. This usually contains DMSO (Dimethylsulfoxide).Wear GLOVES at all times when working with DMSO!!
The antifreeze lowers the freeing point so that small ice crystals form. This prevents damage to the cells caused by large crystals.
The antifreeze we will use contains 10% DMSO, 1% Tween 20 (Detergent) & 4% Formaldehyde (This is the same stuff used by Dr. Frankenfritter so you don’t want it to get inside you - Do you???) Wear Gloves!!!!
Wash your hands when you finish your work!!!!
The DMSO & Tween help the solution reach all the recesses inside the specimen. The Formaldehyde is a relatively gentle preservative which allows you to store your sample for a long time in the fridge. with little apparent change in color etc.
Because most plant parts have air spaces, a vacuum is drawn with the sample in the antifreeze solution.This should last 8-24 hours.
Link to Microtome Website http://home.primus.com.au/IP-PWPSTORE02/64/royellis/microt.htm