X-Message-Number: 11092
Date: Wed, 13 Jan 1999 14:59:56 -0700
From: "Tony B. Csoka" <>
Subject: FWD: Freezing human eggs

> Contact: Claire Bowles
>        44-171-331-2751
>        New Scientist 
>        A Woman's Egg Can Be Freezer Friendly, If You Go Easy On The Salt 

>        Human eggs don't freeze well -- or so IVF specialists have always 
thought. But biologists in New Jersey now say they have overcome the problem,

>        by abandoning the idea that eggs should be frozen in a solution that 
resembles body fluids. 

>        The researchers have obtained high survival rates after cryopreserving 
and then thawing mouse eggs. If their technique also works with human eggs,

>        then women whose eggs are frozen -- before they undergo chemotherapy 
that damages their ovaries, for example -- will have a better chance of
>        becoming mothers. 

>        Fertility centres routinely freeze sperm and embryos, but only a few 
births have been reported using frozen eggs. James Stachecki of the Institute 

>        Reproductive Medicine and Science of St Barnabas Medical Center in West
Orange, New Jersey, wondered if the saline solution used to freeze eggs
>        was to blame. 

>        Cells must be surrounded by a more concentrated solution during 
freezing. This pulls water out of the cells by osmosis and reduces the chances 
of ice

>        crystals forming, which can damage cell structures. Cryobiologists 
usually use a saline designed to mimic body fluids. 

>        But Stachecki suspected that sodium ions from such solutions were 
getting into the eggs and poisoning them. Instead, he decided to try a solution

>        containing choline ions, which do not readily cross cell membranes. 
Choline is an organic molecule found in many plant and animal tissues, and is a

>        constituent of B-complex vitamins. Cryopreservation experiments on 
other types of cells using choline solutions had produced promising results. 

>        Using hundreds of mouse eggs, Stachecki and his colleagues found that 
the choline solution allowed 90 per cent to survive freezing and thawing. And

>        when the surviving eggs were fertilised, 60 per cent developed into the
ball of cells called a blastocyst (Cryobiology, vol 37, p 346). 

>        "The results are very encouraging," says Roger Gosden, a reproductive 
biologist at the University of Leeds. With conventional saline, only 50 per

>        cent of eggs survived freezing and just 10 per cent of those fertilised
went on to form a blastocyst. 

>        "The plan now is to do more work in humans to test how well it works," 
says Stachecki. Several women have already volunteered to donate their eggs

>        for the research. If the new technique works for humans, it may allow 
easier egg banking at fertility clinics.

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