3.3.5. Sectioning and mounting

Use the following procedure to embedded tissues and section with a microtome.  The resulting sections should then be mounted onto glass slides. In general, cutting tissue sections needs training and practice. Therefore, we recommend consulting a person who is experienced in histological techniques when using a microtome the first time.

  1. Remove (trim) excess parts of the paraffin block containing the tissue to a few millimetres around the tissue. Use a scalpel for trimming.

  2. Fix the trimmed paraffin block onto the specimen holder of the microtome for preparing tissue sections. The procedure of fixing the paraffin block depends on the model of the microtome. Please refer to the manual of the microtome.
  3. Trim the paraffin block on the specimen holder again to make the upper and lower sides of the block parallel to each other.
  4. Mount the specimen holder onto the microtome.
  5. Cut the paraffin block into 5 µm thick sections. You can adjust the thickness of the sections to your purpose and type of tissue. For example, you may have to use thicker sections when preparing hindgut tissue that is filled with solid waste, such as pollen shells.
  6. Mount the sections on a commercially available, glass slide coated with aminosilane (APS) or equivalent. Place each section on a separate slide because it is important to have several slides with the same tissue sample sections to allow for different stains to be used, and to provide enough samples for controls.