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Assisted hatching is a micromanipulative ART procedure designed to help embryos “hatch out” of their “’shell”, the zona pellucida, and implant into the endometrium. Once the embryos mature and are ready for transfer, the embryologist gently makes a small hole in the zona pellucida. This opening can be made with a microscopic needle, chemically using Acid Tyrode’s solution, or with a laser. The assisted hatching procedure does not damage the embryo. Opinions differ as to the effectiveness of assisted hatching and not all programs offer the procedure. It is often used in older females, those who have failed previous IVF cycles, and when poor embryo quality or abnormally thickened zona pellucidae are present.
At the blastocyst stage of development, the embryo is a hollow ball. – the thin, outer layer is called the “trophectoderm”, which later will form the placenta and other supportive
Because blastocysts have a higher implantation rate than day 3 embryos, fewer are transferred to the uterus, reducing the incidence of multiple births. They also have a higher implantation rate than day 3 embryos. However, blastocyst transfer is not appropriate for all IVF cycles/couples. As the embryos develop beyond day 3, invariably some do not survive the extended culture. There must be enough viable embryos on day 3 to risk culturing for the additional days. For example, if a couple has only 2 embryos on day 3, we would not risk loosing all viable embryos by extending the culture to the blastocyst stage. On the other hand, if a couple has 6 embryos on day 3, we would be more likely to wait for blastocyst development. ART Links |
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membranes. A blob of cells called the “inner cell mass” are the cells that will go on in development to form the fetus itself. Blastocysts usually require at least five days to develop, and are “heartier” than day 3 embryos. Natural selection works to insure that only the “strongest” embryos survive to the blastocyst stage.