vitrification

The techniques of vitrification of oocytes and the subsequent warming process being used today are now producing results far superior to the results that are obtained with slow-freezing techniques, and it would seem that this is the method of female fertility preservation that will be widely used in the near future. The reported success of the use of this method should stimulate a renewed debate on oocyte storage for fertility preservation without a medical indication.

While men are capable of manufacturing 1000 sperm in the space of one heartbeat up to a ripe old age, the female of the species steadily but surely loses her eggs from birth to menopause, with an accelerated loss from the midthirties onward. Accompanying this loss of eggs is an equally severe decline in egg quality with age. Consequently, female fertility potential rapidly dwindles from the age of 37 on.

Sperm cryopreservation was first successfully performed (in snow!) more than 200 years ago. The cryopreservation of oocytes for fertility preservation has been attempted much more recently but has undergone a complex history, which has been largely unsuccessful. The slow-rate freezing of oocytes results in extracellular and intracellular crystallization of ice, which can cause irreparable damage to the spindle. In addition, the egg is particularly sensitive to chilling injury, which assuredly can occur with most slow-freezing protocols.