Vitrification of cell embryos

For IVF ( in vitro fertilization ), there is often a need to conserve germ cells or embryos. There are two main types of cryopreservation of embryos: slow freezing and vitrification.

Types of cryopreservation of embryos

Slow freezing is a more outdated method, in which the method of freezing water from an embryo using liquid nitrogen is used. In this embryo with cryoprotective media (protecting from damage by cold) is placed in a plastic straw and cooled to 0.5 degrees per minute to -7 degrees. Then they touch the straw with a pair of tweezers moistened in liquid nitrogen (freezing the water from the embryo), cool slowly to -35 degrees, then transfer to liquid nitrogen and complete cooling to -196 degrees.

The disadvantage of the method in the method itself is that on the one hand, dehydration helps to survive the embryo upon freezing, and on the other hand it can destroy it precisely because of dehydration - the water associated with proteins also leaves the body, which destroys the cells.

A more modern method is vitrification of embryos. At the same time, slow freezing is eliminated with the formation of ice crystals. A straw made of plastic with more reliable and complex cryoprotective media is immediately placed in liquid nitrogen, using the rapid transition of all water to the vitreous state. With this method, there is no dehydration of the embryo and it easily tolerates unfreezing without damaging.

With slow freezing, the death of embryos can be from 25 to 65%, and in case of vitrification - only 10-12%. In liquid nitrogen, embryos can be stored for up to 12 years. Frozen embryos are not always necessary: ​​they usually fertilize several eggs , but no more than 2-3 embryos are placed in the uterus for implantation. But frozen embryos can be used with time, as not always after IVF pregnancy immediately comes, and spare embryos are needed for the following attempts. If the pregnancy has occurred, then with the consent of the parents frozen embryos can be destroyed.

Vitrification of eggs and spermatozoa

In addition to freezing embryos, it may be necessary to freeze and germ cells. Vitrification of sperm may be necessary before surgery for a man, after which his ability to fertilize may be reduced. Before freezing, the sperm is checked and only one is used that contains spermatozoa with good mobility and without damage.