The year 2012 began with intense preoperative preparations for the first ovarian transplant in China. As the highlight of 2012, our Reproductive Center put a lot of effort into preparing for this event, with clinical, nursing and laboratory all making adequate preoperative preparations for the ovarian transplantation. As for the laboratory, our preparation is focused on the cryopreservation of the ovaries. In science fiction movies, it is common to see people frozen at ultra-low temperatures to suspend their lives, and then thawed and brought back to life several years later. Is this achievable? We regret to inform you that, at least for the time being, it is not possible. What is currently possible in our Fertility Center laboratory is to freeze eggs, sperm, and embryos in ultra-low temperature and then thaw them for application when needed. A common problem involved here is how to protect these cells from “frostbite” during the freezing process. It is because the cells contain a large amount of water, and during the freezing process this water will freeze into ice crystals, and the production of ice crystals causes damage to the cell structure. In order to solve this problem, scientists have come up with a solution, that is, before freezing with cryoprotectants for these cells, the cells inside the water with a protective agent instead of out, these protective agents in the freezing process will not form ice crystals, thus protecting the cells. As you can imagine, the smaller the cell, the easier it is to replace the water inside, the larger the cell and the larger the tissue block, the less likely it is to complete the process. Sperm cells are much smaller than egg cells and embryo cells, so sperm freezing is relatively easy, while egg freezing is much more complicated. If you want to freeze the entire human body, it is even more complicated, technically speaking, to replace all the cells of the entire body with this protective agent before freezing is possible, but the human body is so huge relative to a cell, the total number of cells in the general human body is 75-100 trillion, the surface layer has not yet completed the process of replacement, the tissue inside has long been frostbite. Therefore, at least for the time being, science and technology are not yet able to freeze the whole person. So how is the freezing of the ovaries achieved? As a female reproductive organ, the ovaries have two important functions: one is to produce reproductive cells – eggs – and the other is to secrete estrogen and progesterone. The purpose of freezing the ovaries is actually to store these two functions and to thaw them when needed and then transplant them back into the human body to perform these two important functions again. As mentioned earlier, the most important thing about cryopreservation is to avoid frostbite to the cells, and the same is true for ovarian cryopreservation. There are many operational details in the technical process in order to reduce the damage of freezing to the ovarian tissue. In addition to carefully reading the instructions for ovarian cryopreservation sent by Dr. Silber, we also reviewed many foreign publications and analyzed different methods of freezing and finally chose to use the safer “vitrification method We finally chose to use the safer “vitrification method”. What is the vitrification method? As mentioned above, in order to reduce cell damage during the freezing process, it is necessary to use cryoprotectant to replace the water inside the cells. When the concentration of cryoprotectant is high, it will show a viscous non-crystalline vitrification state under ultra-low temperature, and in the vitrification freezing method, the cells will show this state, and no ice crystals will be produced during the freezing process, so there will be less damage to the cells. After selecting the protocol, we made two sets of plans to ensure that everything would be safe, one with cryoprotective solution according to Dr. Silber’s instructions and the other with commercial cryoprotective solution, and we made standardized protocols for both protocols and printed them out and posted them next to the operating table to facilitate operation. All the instruments needed for cryopreservation were also prepared in advance. The night before the procedure, I went over the steps in my mind and thought through the details of each step. On the day of the procedure, I was confident when the remaining tissue from the ovarian transplant was handed over to me for freezing, and the entire procedure was praised by Dr. Silber, which was a tribute to the efforts of our entire lab team for this procedure.