Assisted HatchingIn order for the advanced embryo to implant in the uterine wall and to continue development, it must break free of its shell, which is called the zona pellucida. Some embryos grown in the laboratory may have a harder shell than normal or may lack the energy requirements needed to complete the hatching process. The embryologists can help these embryos achieve successful implantation through a technique called assisted hatching. On the third
or fifth day of laboratory growth and shortly prior to uterine transfer, a small hole is made in the zona pellucida of the embryo with a specially fitted
laser microscope. Through this opening, the cells of the embryo can escape from the shell and implant at a somewhat earlier time of development, when the uterine lining may be more favorable.
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