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Assessing the Medical Risks of Human Oocyte Donation for Stem Cell Research: Workshop Report
travels through the back of the vagina and into the ovary, where, under the guidance of ultrasound technology, the eggs are aspirated. Typically, a woman who has undergone the usual hormone treatment will have a dozen or so eggs that can be collected.
Once the oocytes have been retrieved, they are prepared for fertilization. Each egg is placed in a culture medium along with prepared sperm cells and incubated for about 18 hours. At the end of this time, the eggs have been fertilized, and they are put into a growth medium for another 1-2 days, until they have reached the four- to eight-cell stage. At this point, they can be transferred into the woman’s uterus, although a number of assisted reproduction facilities wait another two days until the fertilized embryo has reached the blastocyst stage, with approximately 100 cells. At this stage, the embryo can be used for the collection of embryonic stem cells from the blastocyst’s inner cell mass.
Years of experience with assisted reproduction have identified a number of potential risks associated with egg donation (see Box 1-1), which fall into three main categories. The first category of potential risks arises from the hormone regimen that women are given to stimulate egg production. The risks include ovarian hyperstimulation syndrome; breast, ovarian, and endometrial cancers; and perhaps problems with long-term fertility. The second category is associated with the surgical procedure, including the anesthesia, and involves many of the same issues that anyone having surgery faces. The third set of potential risks is psychological in nature and includes anxiety, mood swings, and post-donation adjustment.