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Vitrification Explained

The Vitrification technique

Unlike sperm, which has been successfully frozen and used for many years, eggs contain a large percentage of water (~90%). The largest factor that determines whether or not an egg will survive being frozen and subsequently thawed is the formation of ice crystals from that water during the freezing process.  Historically, eggs were slowly cooled from room temperature down to -196 °C, the temperature at which they will be stored (the temperature of liquid nitrogen).

During this cooling process the water in the eggs would form ice crystals. Such crystals can damage the cellular structure of the egg and result in the egg not being usable when thawed. The freeze and thaw survival rate with the old method was in the range of 30%, which is not very encouraging.  Recent developments in the field have allowed our laboratory to adopt a new technique called vitrification.

In this process the eggs are first prepared by being dehydrated and placed in specially formulated vitrification media (akin to using anti-freeze). The eggs are then rapidly cooled from room temperature to -196°C such that the eggs are preserved in a glass-like state ( hence vitrified).  This technique has resulted in drastically improved freeze and thaw survival rates of over 90%.

How many eggs should you freeze?

Your age and personal egg reserve will all affect the number of eggs we recommend you freeze. However, research has proven that a minimum of 30 eggs is needed to guarantee a fertilised embryo for a successful pregnancy.

The number of stimulated cycles you would need to produce 30 eggs depends on your follicle count. To help you work out how many eggs you would need to collect and freeze, our Embryologists have created this simple calculator.

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Under 35 years





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