Freezing of human gametes and embryos is of great importance in IVF practice. The general approach to minimize the risk of multiple pregnancy in IVF applications is to transfer up to 3 embryos. The first question that comes to mind in this case is how to evaluate the excess embryos obtained. Freezing the excess embryos thus obtained gives the patient an economic and psychological advantage. Furthermore, the patient does not need any treatment when the frozen embryos will be transferred. Embryo freezing can also be considered as a procedure that increases the chances of success in IVF applications.
Embryo freezing and thawing process, after the embryos are stabilized with chemical substances (cryoprotectant), are cooled and stored in liquid nitrogen at -196 degrees Celsius, and after thawing, they are removed from cryoprotectant medium and taken into special culture media for further development. Both procedures should be performed with extreme caution. In order to preserve the cell structure, the cells should lose water at low speed and thus be frozen by slow cooling method. During cooling, pure water in the medium solidifies and consequently becomes more dense than the cell. However, when small volumes are cooled by slow cooling, this time overcooling occurs and ice crystals are formed even though the solution is cooled to below freezing temperature. If this process is too sudden, the embryos will be damaged. To prevent damage, ice crystals are formed very slowly with a technique called seeding.
In routine IVF and microinjection applications, embryo freezing and pregnancy rates vary between 15-25%. If pregnancy is achieved in the same cycle and the remaining embryos are frozen, the pregnancy rate is 40%. frozen embryos from couples taking permit Turkey "can also be stored in liquid nitrogen for 3 years with a law enacted in 1997.
Let us explain the effect of freezing with an example. Let's assume that 6 embryos were obtained from one woman during the same menstrual period and 3 of them were transferred and the remaining 3 were frozen. With the embryos transferred, get a singleton pregnancy. This baby will be born after 40 weeks. Imagine that once the baby reaches the age of 3, a singleton pregnancy is achieved using pre-frozen embryos this time when her parents decide to a second child. In this case, it is possible to have children at different periods from embryos obtained from the same abdomen.