The embryo development using cryopreserved oocytes through the vitrification technique is equally effective to that of the embryos derived from fresh ova. The oocyte cryopreservation is of great importance in the assisted reproduction, especially in cases in which it is almost imperative as in egg donation programs, in case of sperm absence from the husband, as well as in cases of cancer treatment and preservation of fertility due to increased age.
The technique of oocyte and embryo cryopreservation through vitrification has been developed in recent years and constitutes a safe cryopreservation method with impressive efficiency and high rates of successful thaw. With the technique of vitrification the freezing process takes a few minutes, without putting the embryo / ovum to the more invasive procedure of long freezing, which was the most common method of cryopreservation until recently.
The oocyte freezing was unfeasible until recently, due to their fragility. Today, through the vitrification method the oocytes are being frozen successfully and every woman can freeze five to ten eggs – this is the amount required for the success of the method - and use it whenever she wants if for any reason her ova then can not be fertilized.
Already, in countries, where the vitrification is carried out, more than 1,400 children were born, while our country is the sixth in the world and the third in Europe to have a child with this method. An important advantage of this method concerns the cases of chemotherapy or the submission to radiation, in which the ovaries are being destroyed, while premature menopause occurs too. Thus, the woman may proceed to ova vitrification before starting the treatment, which can be used when it is competed and of course when the drug levels in her body decrease and the pregnancy is safe.
From a moral standpoint, the main advantage is that in case that the woman never wishes to use them, she can decide to destroy the eggs, without the ethical dilemmas of the cases of destroy of fertilized embryos. The same moral dilemma does not also exist in the case of couple's separation, or death of either the man or the woman.
Generally, vitrification is the process of converting a material in a glassy form which is free of crystalline structure. In the freezing process, an increased concentration of cryoprotectant is being used with a parallel rapid decrease in temperature. Thus, the ovum is protected from the possible adverse effects that the cryoprotectant medium may have, while the excessive dehydration is avoided, while more importantly, the ovum is not jeopardized by the creation of intracellular ice crystals.