Dale Gunn
Web Developer, Software Engineer, and Student in the United States
For an embryo to implant into the lining of uterus, it must essentially divide to where it forms a multi-cell embryo with fluid cavity (blastocyst). This blastocyst is coated with a gel-like material called 'Zona' or 'Zona Pellucida. In order for blastocyst to implant into uterus, its cells must break through Zona. This process is known as hatching.