When using cryotubes to store samples, it is strictly required to store the cryotubes in the gas phase layer of liquid nitrogen or in a refrigerator. If the cryopreservation tube is stored in liquid nitrogen, there is a certain chance that liquid nitrogen will seep into the interior of the cryopreservation tube. During recovery, the vaporization of liquid nitrogen leads to an imbalance of pressure inside and outside the tube, which can easily cause the cryopreservation tube to explode and have biological hazards.