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The Endowment for Human Development
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Early Blastocyst

3 days

Source: Centro Riproduzione Assistita, Catania, Italy.

Note:

Once the morula develops an inner cavity, the embryo has achieved a new developmental milestone and is called a blastocyst.

Note:

The cells lining the perimeter of the embryo will help form the placenta and are called trophoblast cells. These cells bring water, minerals, and amino acids from the nutrient-rich environment outside the embryo into the blastocyst cavity where they can reach the cells of the inner cell mass.

Label Key:

1. zona pellucida
2. trophoblast
3. early blastocyst cavity
4. inner cell mass
All ages referenced to fertilization, not last menstrual period.
Morula: Twelve-Cell Embryo
Morula: Twelve-Cell Embryo
The Human Morula
The Human Morula
Early Blastocyst
Early Blastocyst
Blastocyst
Blastocyst
Blastocyst with Inner Cell Mass
Blastocyst with Inner Cell Mass
Hatching Blastocyst
Hatching Blastocyst
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