Isopentane is a liquid hydrocarbon at room temperature. It is extremely flammable and should be stored in a flammable cabinet. Isopentane does not boil when it comes into contact with tissue because it has a freezing point of -160°C and a boiling point of 28°C. (4) Tissues immersed in isopentane cool faster than those immersed in liquid nitrogen because there is no boiling effect. The actual method used may have had a detrimental effect on the results. The isopentane was placed in a 50 ml beaker that just fit the stylet and the liquid just covered the surface of the tissue. This may have caused the tissue to freeze more slowly as the thin layer of isopentane was heated through the tissue and to room temperature. Some studies also suggest that movement while in isopentane may yield better quality results. This can be improved by using a larger container of isopentane or by using a smaller piece of tissue. An advantage of isopentane over liquid nitrogen is that the tissue is frozen at approx. -165 degrees C compared to approx. -200 degrees C for liquid nitrogen. This means that the temperature difference between the cryostat and the tissue is not as large, which reduces brittleness and the possibility of the tissue