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University
of Manitoba HomeMicroscope Slides
In Biology, you will be exposed to the following types of slides:
Prepared slides consist of whole organisms, or sections (thin slices) of organs or tissues. In the case of sectioned material, an organ or piece of tissue is first killed and 'fixed' in a preserving material. It is then infiltrated and embedded in paraffin or plastic. The resulting block is cut into thin sections (usually 4 - 10mm thick) on a microtome and the sections are mounted on glass slides. The paraffin is removed and the material is stained usually following a specialized technique to emphasize a particular structure or substance. Finally, the preparation is covered with a thin layer of permount and a cover slip is placed on top.
II - Fresh Mounts
Fresh mounts of biological material may involve whole organisms, free-hand sections cut with a razor blade of part or all of an organism, or material which is mechanically or chemically teased apart. The material is placed in a drop of physiological saline or water in the center of a clean slide. Some care must be taken in lowering the cover slip in order to avoid trapping air bubbles. The difficulty is overcome by first allowing only one edge of the cover slip to rest on the slide and, while supporting the cover slip with a needle, slowly lowering it over the preparation. Since this type of preparation will dry up, a drop of saline or water must occasionally be added along one edge of the cover slip. Alternatively you can reduce evaporation by ringing the edges of the cover slip with a thin film of vaseline.
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