The egg cells or ovum and sperm can be preserved for years. This technique of freezing eggs and sperms is called cryopreservation. Certain concentrations of cryoprotectants are used to freeze the cells.
EGG FREEZING
As a woman grows older, her fertility decreases considerably. Her ovaries start to age and by the time she is 35, she has lost approximately a thousand eggs as a result of her monthly menstrual cycle. By the time she is 40, she has only ten percent of her ovarian reserve intact. But these eggs are usually of poor quality. This might lead to failed attempts of reproduction or fertilization. Moreover, the fertilization of these low-quality eggs often leads to chromosomal defects in the child. Thereby, it might be a good decision for a woman to freeze her eggs while she is still at her fertile. This will increase the probabilities of giving birth to a healthy child in future. Two methods that are practised for egg freezing are:
1. Slow Freezing
2. Vitrification
Both inseminated and non-inseminated eggs can be frozen.
Why are inseminated eggs frozen?
• If there are surplus embryos left after an IVF cycle.
• If a couple wishes to donate extra fertilized embryos to a couple who has problems in conceiving.
Why are non-inseminated eggs frozen?
• If the woman is to undergo chemotherapies or radiation: freezing her eggs is a good option since most of her eggs will be genetically abnormal after her treatments begin.
• If a woman is planning on getting her ovaries removed due to some medical reasons.
• Other medical reasons.
• Lifestyle measure.
The eggs and embryos are preserved in special solutions and stored in temperatures around -400-degree Fahrenheit. When a pregnancy is desired, the egg is thawed in an incubator and placed inside the uterus of the woman. The survival rates of these eggs lie between 90 to 95%.
SPERM FREEZING
Just like women, the fertility of men is also affected by a number of factors. One of these factors is age. With age, the quality and quantity of sperm decrease. Either is the sperm of low quality or the quantity of sperm in the ejaculate is considerably less.
Why are sperms frozen?
• If the male is to undergo chemotherapies or radiation: freezing his sperms is a good option since most of his sperms will be genetically abnormal after his treatments begin.
• If the male is planning on undergoing vasectomy.
• Lifestyle measure.
• Other medical reasons.
• If a male is willing to donate his sperms.
Before sperm freezing, a number of genetical tests and semen analysis are done. The results of the tests will determine if the sperms can be preserved and thawed when required. After several rounds of tests, the sperms are cryopreserved in temperatures around -196-degree Fahrenheit. When a pregnancy is desired, these sperms are thawed in laboratory and injected into the egg cell after a couple of hours. Usually, the sperms can be frozen up to 28 years.
