Freezing(Vitrification) – Embroys & eggs

Freezing (Vitrification)

Infertility is a major problem that one in every seven couples faces. Sometimes the problem is with the male partner’s sperms, while in some cases the problem is with the embryos or eggs of the female partner. Assisted Reproductive Techniques are therefore used to help such couples reproduce by completing the fertilization inside the womb or outside the body. For use in such techniques, the sperms or eggs sometimes need to be preserved for later use. Also, sometimes it is necessary to store and preserve the sperms and eggs before a major surgery, so that they can be used later if the surgery alters the state of fertility in any way. Third, many females prefer childbirth at a later age after they have stabilized their careers, and they can preserve their unfertilized embryos for use at a later date. Finally, many women donate their eggs to others who might need them for conceiving.

Initially, slow freezing was the generally accepted technique for preservation of these reproductive tissues for later use. This process worked much better for preservation of sperms. But because of the larger size of embryos, their functioning was often mutated and modified as a result of first freezing and then thawing, leading to poor rates of survival. Subsequent research led to a new technique called vitrification, also referred to as fast freezing. Vitrification is now widely used for cryopreservation of unfertilized embryos and eggs.The biggest change in this method is that the freezing is done very rapidly, so that there is no formation of ice in between cells, so there is no damage to the inner parts of the cells.

There is a liquid contained inside the oocytes, which needs to be replaced with a cyroprotectant. This substance protects the inner cells of the embryos from the ill effects of freezing temperatures. Increasingly greater concentrations of these cyroprotectants are used, which takes the temperature of the egg from the ambient temperature of 37°C to -196°C. These frozen cells are then preserved in liquid nitrogen and kept safe for later use. When the egg is needed to be used, the temperature is increased to the culture temperature, before they can be used as needed.

When a couple goes to a fertility clinic for infertility treatment, the price quoted to them often doesn’t include the cost of vitrification or freezing-thawing costs. For example, if sperm needs to be preserved, the cost would include doctor appointments, blood samples, and the annual storage fee. On the other hand, the vitrification of eggs and embryos is a much costlier alternative. Anyone wishing to go in for assisted reproduction techniques should find out about these costs in advance.

Any effort at preservation of eggs should be done not later than 35 years of age, because after that there is a drop in egg quality. Vitrification is a scientifically proven technique with hundreds of happy users, so in case you wish to preserve your eggs or embryos for later use by you or someone else, then vitrification is a dependable technique.