Can Gametes Be Frozen Like Ice
Cryopreservation is a technique in which various cells of the body, sperms, and ovaries; ovarian or testicular tissue can be frozen at an extremely low temperature to avoid its degradation and can be used in future, whenever required. The most effective solution used to freeze cells is liquid nitrogen, which freezes cells at a permissible temperature of -196̊ C. The cells or the gametes are frozen in presence of a cryoprotectant, which protects the cells from the havoc caused due to the formation of ice crystals, which basically damages the plasma membrane of cells and disrupts osmotic pressure. Cryopreservation enables the cells or the tissues to remain viable for a very long time, which may range from 5 to 10 years. With the effective use of cryopreservation, we can store and freeze not just the individual gametes but also fused embryos.
Why is it used?
- To use eggs and sperms for future IVF procedures.
- When multiple eggs are harvested, this can be used for a number of IVF cycles.
- Intact embryos can be used as donors for any other couple.
- To protect the egg’s fertility, in case of a cancerous condition.
- To store sperms in cases of low sperm count, poor motility or sterility.
- For people undergoing various surgical treatments like vasectomy or tubectomy.
When gametes or tissues are cryopreserved, they are subjected to no physical or biological activity and are suspended. When cryopreservation is done, the gametes from both the parents are taken and are frozen at an extremely low temperature. A solution, also known as cryoprotectant protects the cells from the mechanical stress which can result due to crystallization. The samples are then thawed before they can be used.
When gametes or tissues are cryopreserved, they are subjected to no physical or biological activity and are suspended. When cryopreservation is done, the gametes from both the parents are taken and are frozen at an extremely low temperature. A solution, also known as cryoprotectant protects the cells from the mechanical stress which can result due to crystallization. The samples are then thawed before they can be used.
For a regular or a normal IVF procedure, the foremost step that is involved is the stimulation of ovaries, followed by egg retrieval. The eggs thus retrieved, can be stored effectively and frozen which can be of use in further IVF procedures if first attempt fails. The frozen eggs can also be used as donor eggs, as per the consent of the female whose eggs have been retrieved. Embryo cryopreservation applies the same method, differing in the manner that in spite of individual gametes, fused embryos are frozen and stored. This enables the parents to use embryos for a second pregnancy if the first one is a success.
How embryos can be stored?
- Consent needs to be written if the couple wishes to store egg and sperm. This type of consent is also made between the donor couple and the intended parents if a donor embryo is used.
- Both the male and female who donated sperm and egg are screened beforehand, to look for any infectious condition, like, AIDS, Hepatitis, etc.
- The gametes are quarantined for a period of 6 months to avoid any spread of infection.
- After an IVF treatment, the leftover embryos are frozen in a cryoprotectant, probably glycerol or ethylene glycol and are stored in tanks of liquid nitrogen.
- Embryos are then thawed whenever they have to be used again.
- The two basic methods employed for the freezing of gametes is slow freezing and fast freezing, also known as vitrification.
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