| Abstrakt: |
This paper describes a method for obtaining ultrathin frozen sections of fixed and unfixed tissues using a slightly modified LKB Cryokit. With these modifications, the specimen temperature is maintained at −180°C, the knife is stabilized at −100°C and the temperature within the Cryokit chamber is regulated to −120°C. Sections of glutaraldehyde-fixed tissues are routinely collected from liver, kidney, spleen, cartilage, tendon, muscle, thyroid and intestine. Sections may be negatively stained with 2% ammonium molybdate or 1% phosphotungstic acid. Positive stains, such as lead or uranium salts, do not produce results of similarly good quality. Although it is relatively easy to obtain thin sections from frozenunfixedtissues, these sections are difficult to preserve during subsequent procedures. Morphologically, the best results can be achieved when sections are cut with a dry knife and collected directly on a supporting grid for electron microscopy. After drying, these sections may be viewed unstained or negatively stained with ammonium molybdate or phosphotungstic acid. This study suggests that routine sectioning offixedtissue by cryomicrotomy can be recommended as a method to increase the electron microscope laboratory productivity and to enhance the application of additional cytochemical techniques. Cryomicrotomy ofunfixedtissue cannot be considered a routine procedure but the possibility of it becoming so has been greatly increased. |
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