The developing embryo is encased in a clear "shell" called the zona pellucida. This keeps the cells of the embryo together and protects the embryo until it can implant into the wall of the uterus. However, before it can implant, it must "hatch" out of this shell so that the embryo's cells can bind to and invade the lining of the uterus. In the laboratory, we can use micromanipulation techniques to make a small hole in the zona pellucida, which will allow the embryo to move easily, hatch and implant in the uterus.
Studies have shown that this technique seems to particularly benefit women who:
- are age >37 years old
- respond poorly to stimulation medication
- have had previous repeated IVF failure, or
- have increased thickness of the zona pellucida.