1 doctor weighed in:

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

1 doctor weighed in
Dr. Marybeth Lambe
Travel Medicine

In brief: 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.

In brief: 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.
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