Cryopreservation
and Cryotransfer

Cryopreservation is a common method used in fertility treatment. In Germany (country-specific), several different materials can be frozen:

Unfertilised eggs:

With unfertilised eggs, there is still a relatively high risk that they can be damaged during the cryopreservation process. Unfertilised eggs have a much greater sensitivity to the freezing process due to their higher water content (compared to fertilised eggs). Water crystals that form during the freezing process can therefore cause more damage. Nevertheless, the frozen, unfertilised eggs are still valuable and can be used to conceive children in the future.

Fertilised eggs in the pronuclear stage

By using computer-assisted temperature programs that control the freezing process and special cryopreservation procedures in which cells are mixed with a membrane-protecting medium (the cryoprotectant), the cells are put in a state that ensures that they can be stored over long periods (years) without impairing their viability.

Embryos

In Germany, under the Embryo Protection Law, embryos may be frozen only in exceptional cases.

Sperm

As part of infertility treatment, cryopreservation of sperm may be necessary due to the prolonged absence of the partner, a health condition, or difficulty on the part of the man to provide sperm on demand (psychological impotence).

Testicular tissue

Testicular tissue obtained in a biopsy (see TESE) can be frozen for later sperm retrieval. This allows for hormonal stimulation of the ovaries in the woman without time restraints. In addition, multiple biopsy samples can be individually frozen for several ICSI attempts.

Ovarian tissue

Thanks to state-of-the-art cryopreparation techniques, it is possible to carefully freeze tissue without impairing the physiology of the cells. The thawed, intact ovarian tissue can then be re-implanted after several years of cryopreservation (autotransplantation). It is also possible to remove the eggs that have matured in the ovarian tissue from the cryopreserved tissue at a later date and use these for artificial insemination.