How many days after fertilization does the fertilized egg become a blastocyst? then embryo? what implants-the blastocyst or embryo?

The process: As the fertilized egg divides, it is first known as a morula. Approximately 5 days from first fertilization it forms into a hollow ball known as a blastocyst. This blastocyst implants and begins to sort itself out into different layers--the inner group becomes the embryo and the outer layer will work to nourish and protect. At approximately 6-7 weeks from time of fertilization, an embryo begins.