Sectioning is performed using microtomy or cryotomy. Sectioning is an important step for the preparation of slides as it ensures a proper observation of the sample by microscopy.
– Paraffin-embedded samples are cut by cross section, using a microtome, into thin slices of 5 micrometers. Glass slides are covered with a solution that contains an additive in order to keep the section attached onto the slide. Slides are then placed onto a hotplate in order to ensure a uniform spreading of the sample. Once the slides are heated, the residual liquid is removed by hand. The slides are then dried at room temperature.
– Frozen samples are cut using a cryostat. The frozen sections are then placed on a glass slide for storage at -80°C.
Bioalternatives evaluates the suitable fixation and sectioning conditions according to your sample and to your study.
The choice of these preparation conditions is crucial in order to minimize the artifacts. Paraffin embedding is favored for preserving tissues; freezing is more suitable for preserving DNA and RNA and for the labeling of water-soluble elements or of those sensitive to the fixation medium.