Ultramicrotome Reichert-Jung Ultracut E,
In histo- and pathology it is common to embed tissue in paraffin. To cut the paraffin blocks, usually a rotary microtome is used, which may or may not be electrically driven. With this technique the coupe thickness is limited to approximately 3µm. With a hard paraffin and the right conditions 2µm is sometimes achievable, but these are exceptions. For a more detailed image of the tissue, a thinner cut is necessary. To achieve this, tissue has to be embedded with synthetic resin. This material is much harder than paraffin and can therefore be cut a lot thinner. Cutting synthetic resin requires a different kind of microtome and knives. A stable rotary microtome, with retraction capability, and the ultramicrotome are the appropriate devices for this purpose. Cutting is done with diamond or glass knives. The big advantage of glass is that the knives can be made themselves and are not inferior in sharpness to the rather expensive diamond knives. However, the service life of a glass knife is much lower than that of a diamond knife. The making of glass knives can be viewed on this site, click here!
The ultramicrotome is basically designed to make sections for the electron microscope. A coupe thickness of 70nm is common here. For this purpose tissue is molded in epoxy resin and cut with diamond or glass on a waterbed. In the video below the cutting of epoxy (Epon) is shown, but also the cutting of a GMA (glycol methacrylate, Technovit) plastic. With the latter technique, the coupe is removed dry from the knife and then stretched on water.
For a 'user manual' of the microtome I refer to the download page.
Epon cutting on the Ultracut E (click on the image),
Technovit 7100 cutting on the Ultracut E (click on the image),
Usage experiences of the author,
The ultracut is a heavy machine and it certainly deserves the attention to put it on a solid surface. My house has wooden floors and when there is a strong wind outside I can't cut anymore because the microtome just moves too much. On the outside you don't see any of that of course but looking through the microscope at the glass knife you can see everything moving. I know from an American friend who lives next to an Interstate that he finally sold his microtome because his house was too close to the road and every time when a truck passed the house, it vibrated and he couldn't cut anymore. This microtome was previously sold with a solid table in which the microtome stood on a damped secondary table with a thick sheet of rubber. All intended to prevent vibrations.
The operation of the microtome is very well thought out. The buttons are in the right place and cutting is quite easy.
From an old Leica mechanic I know that this type of microtome is the best ever made. The parts that break are the three bulbs: two fluorescent tubes for the top light and one halogen bulb for the bottom light. Furthermore the rubber drive belt breaks after a while, simply because it ages and cracks. The author has replaced both the bulbs and the drive belt. Look in 'downloads' or click on an image below.
