Now, notice that our blastocyst implants itself along the section of the trophy blast that is adjacent to the inner cell mass. And that's because the inner cell mass needs to be as close to the vascular tissue of the endometrium because it's the inner cell mass that eventually gives rise to that individual, to that organism. Now, as soon as attachment actually takes place, the cells of the trophy blast, these dark purple cells begin to release digestive enzymes. And what these digestive, digestive enzymes do is they dig a hole inside the endometrium that can accommodate that implanting embryo. So the embryo slowly begins to make its way into the endometrium of that uterus. Now, implantation takes place on about the 7th day following fertilization.