Before delving into the specific techniques, the following should be considered with regard to general tissue embedding.
- The paraffin of choice should have a similar hardness to that of the tissue being embedded.
- Melted paraffin should be kept 2-4º Celsius above its melting point; higher temperatures may separate the paraffin components, resulting in difficult ribboning.
- Cold plate temperature should be set between 3° C and -5º C.
- One cassette should be embedded at a time to prevent accidental tissue transfer between cassettes.
- Forceps and molds should be clean and kept warm. Wiping forceps clean between specimens is advised to avoid transfer of one patient's material to the paraffin block of another patient.
- The grossing information should be referenced for the number of tissue pieces submitted as well as special instructions related to embedding orientation.
- Tissue should be embedded in the center of the mold, diagonally, and in an organized line (not randomly).
- The epidermis of all tissue pieces should face in the same direction in the mold, as shown in the drawing.
- Excisions, cyst cross-sections, and large tissue pieces should be embedded flat, with light pressure being applied over the tissue so that complete sections can be obtained during ribboning.
- Embedded tissue should be chilled rapidly on a cold plate to ensure strong paraffin support and adhesion around the tissue.
