Fixation on Histology

At embedding many histotechs think it's best to, "squeeze out the fat" in order to cut the perfect section. When adipose tissue is firmly pressed down inside a mold filled with hot paraffin, the lipids in the tissue are mixed with the paraffin, causing the paraffin to become oily. Sectioning is then difficult, and the sectioned tissue will explode in the water bath.

Therefore, many techs would either pour the lipid mixed paraffin out and refill the mold and continue the embedding process, or they mash the adipose tissue on the hot plate between a paper towel, place inside the mold and continue the embedding process. Either way, the first image below is what is seen by the pathologist under the scope. The adipose tissue is damaged, the cells are undefinable and cell nuclei are displaced.

When adipose tissue is lightly tapped inside the paraffin filled mold, sections are easy to cut, explosions on the water bath doesn't happen as fast and the adipose tissue remains intact, as seen in the second image below. Please gently tap adipose tissue making sure the whole tissue is on the same plane and do not use force! Do not damage the tissue.