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The Endowment for Human Development
The Endowment for Human Development
Improving lifelong health one pregnancy at a time.
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Four-Week Embryo

4 weeks

From The Biology of Prenatal Development.Buy Now

Label Key:

1. hindbrain
2. spinal cord
3. foregut
4. heart
5. midgut
6. midbrain
7. forebrain
8. site of future mouth (stomodeum)
9. chest wall
10. yolk sac
11. hindgut
All ages referenced to fertilization, not last menstrual period.
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
The Body Plan Emerges
The Body Plan Emerges
Right Upper Limb
Right Upper Limb
When does health begin? Find out now.
Buy the Biology of Prenatal Development DVD