Question: what are the steps of implantation?
Answer: Implantation consists of three stages: (a) the blastocyst contacts the implantation site of the endometrium (apposition); (b) trophoblast cells of the blastocyst attach to the receptive endometrial epithelium (adhesion); and (c) invasive trophoblast cells cross the endometrial epithelial basement membrane and invade ...