Oocytes are affected by freezing significantly more than embryos, as they are more sensitive to the processes of freezing and defrosting. Initially, we used the slow freezing method. It has certain disadvantages; for example, the creation of crystal ice inside a cell damages cellular membranes. If such a thing happens, the oocyte becomes unsuitable for further use in fertilisation. During slow freezing, only 75% of oocytes stayed viable. Nowadays, we use the vitrification method, fast freezing, during which intracellular water turns into an amorphic gelatin-like substance. It excludes the risk of damaging cellular membranes. All our specialists complete educational programs learning this technique and undergo further training directly from the technique’s developers. According to last year’s statistics from our clinic, 100% of oocytes preserved their vital signs and quality after defrosting.