Multiple choice How many days after fertilization, the blastocyst attaches to the wall of the uterus? 2-3 days 5-7 days 8-10 days 10-12 days 13-15 days Reveal answer Fill a bubble to check yourself B Correct answer Explanation 5-7 days after fertilization, the blastocyst attaches to the wall of the uterus (endometrium). When it comes into contact with the endometrium it performs implantation.