⑧ Paraffin embedding

Cool and solidify the tissue in paraffin.

Method

Remove paraffin bath IV from the incubator and place it on a hotplate set to 70 °C. Place the paraffin pouring dish (i.e., embedding dish) on the hotplate.
Prepare a device (e.g., alcohol lamp) to heat the tweezer tips used for tissue grasping.
Fill the embedding dish with paraffin. For this process, use clean paraffin containing no intermediate solvent.
Always heat the tweezer tips before grasping the tissue. Grasp the tissue after letting the heated tweezers slightly cool in the embedding dish paraffin.
Remove the tissue from paraffin bath IV, and place the tissue on the embedding dish with the cut side down.
Arrange the tissue with appropriate spaces between each tissue.
Transfer the embedding dish from the hotplate to the laboratory bench. In order to achieve a flat surface for cutting press the tissue down gently with tweezers.
Embed a slip of paper containing the required information about the specimen (e.g., the tissue number) at the edge of the embedding dish.
Once the paraffin at the base of the embedding dish has turned slightly white and hardened, float the embedding dish in a tub filled with tap water.
Blow on the embedding dish. Once the paraffin on the embedding dish surface has hardened and formed a faint membrane, spray the embedding dish with tap water.
Once the paraffin on the surface of the embedding dish has further hardened and formed a skin, immerse the embedding dish in water.
Run weakly flowing tap water into the tub to harden the paraffin.
When the paraffin hardens and contracts it will separate from the embedding dish.