Egg freezing advances

A team of scientists from the University of Bologna in Italy has developed a new technique for freezing human eggs that improves the survival rate after thawing. The researchers, who published their results in the latest issue of the journal Human Reproduction, say they achieved fertilisation rates comparable to those obtained using fresh eggs.

Successfully freezing and thawing human eggs has proved difficult, and only around 30 babies worldwide have been born using this method since it was first introduced 15 years ago. But Dr Rafaella and her colleagues improved success rates by increasing the sucrose concentration (sugar content) in the freezing solution they used. The sugar solution removes water from the egg prior to freezing, reducing the damage caused by ice crystals. After thawing, the researchers managed to fertilise 57 per cent of the eggs using direct sperm injection (ICSI).

Dr Fabbri said the findings would 'offer hope to women who lose their fertility through medical treatments or who may be at risk of premature menopause'. Mohammed Taranissi, head of the Assisted Reproduction and Gynaecology Unit in London, said he thought the main application for egg freezing would be storing donated eggs. 'I think we will see the development of egg banks along the lines of sperm banks' he told the Guardian newspaper.

Another new study has shown for the first time that frozen human ovarian tissue can develop normally after it has been thawed and transplanted into laboratory mice. UK fertility expert Dr Simon Fishel described the advance as 'very exciting', but stressed it was unlikely to be a reliable treatment for at least five years.