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The Endowment for Human Development
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The 4-Week Embryo

3 weeks, 4 days

The 4-Week Embryo [Click for next image]
From The Biology of Prenatal Development.Buy Now

Label Key:

1. brain
2. body cavities
3. somites
4. tail
All ages referenced to fertilization, not last menstrual period.
3-Week Embryo
3-Week Embryo
The Folding of the Embryo
The Folding of the Embryo
The 4-Week Embryo
The 4-Week Embryo
The Folding Heart
The Folding Heart
Four-Week Embryo
Four-Week Embryo
Digestive Tract, 4-Week Embryo
Digestive Tract, 4-Week Embryo
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