Osmosis video - Human development days 4-7

After blastocyst formation at around day four to five, the blastocyst starts to implant into the uterus at around day six or seven. During blastocyst implantation, the trophoblast binds to the endometrial wall with L-selectin and integrin molecules. The blastocyst implants into the decidua basalis, which happens in the secretory phase of the menstrual cycle, also known as the implantation window.