Freezing cells can harm them by forming ice crystals and making them too salty. Scientists studied how cells can be frozen without damage by using a chemical called DMSO. They watched cells freeze and thaw quickly under a microscope and used special light to see the ice inside and outside the cells. They found that the amount of DMSO and how fast cells are cooled or warmed affects how they freeze. This research helps us understand how cells freeze and thaw without getting hurt, which could lead to better ways to freeze cells for medical purposes.