Differentiate into a blastocyst (the embryo itself) and a trophoblast (precursor of the placenta). Normally implantation in the endometrium occurs around six or seven days after fertilization. When implantation occurs outside the uterine cavity, what is known as an ectopic pregnancy has occurred . Fortunately, this implantation failure only occurs in 2% of cases.
Around 97% of ectopic pregnancies take place in the fallopian tubes , specifically in the ampulla, in the isthmus or in the fimbriae. The other 3% are somewhat rarer cases such as in the uterine horn, in the ovary, in the abdominal cavity, th