For an unknown reason the fertilization membrane of an embryo dissolved in the fallopian tube in the first critical period. What complication of pregnancy is possible in this case?

Answer options

1. Invagination of the blastocyst wall
2. Formation of two blastocysts
3. Return of blastocyst back to the ampullary portion of the tube
4. Embryonic death
5. Embryo implantation into the Fallopian tube