Blastocyst embryo, illustration - stock illustration

Illustration of a human embryo at the blastocyst stage, approximately 5 to 9 days after fertilisation. The outer trophoblast layer (red) will implant into the wall of the uterus (endometrium) and go on to form the placenta. The inner fluid-filled cavity of the blastocyst is called the blastocoel. The inner cell mass (embryoblast, orange) will form the embryo