Scientists are developing a new procedure, called germinal vesicle transfer. But in older women, something goes wrong during that second half of meiosis. When older chromosomes duplicate, they tend to distribute themselves unequally, providing the daughter cell with either too many, too few, or the wrong chromosomes. When this happens, a daughter cell usually cannot mature or fertilize. Whereas a normal embryo divides from one cell into two, from two into four, and so on, at some point the abnormal embryo may stop dividing.
Miscarriage soon follows.
Even if the pregnancy goes to term, the baby may have Down's syndrome or some other chromosomal disorder. No one really knows just what in the cytoplasm causes meiosis to go wrong in older women or causes older fertilized eggs to stop dividing. How It Works Germinal vesicle transfer retrieves the germ cells from the older woman before Mother Nature makes a chromosomal mistake and then places the old nucleus in the middle of a young germ cell, with all of its young counterparts. The older woman and her younger donor both take hormones that stimulate their ovaries to produce more than the usual single mature egg in a month. Before the germ cells complete meiosis in each woman, Dr. Zhang and his team remove them from their ovaries.