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The Endowment for Human Development
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Slideshow: Umbilical Cord, Placenta & More

Yolk Sac and Vitelline Vessels

#84, Slide 2 of 35

5 weeks, 2 days

From The Biology of Prenatal Development.Buy Now

Note:

The yolk sac helps feed the embryo until the placenta is operational. It does NOT contain yolk at any time.

Label Key:

1. yolk sac
2. yolk stalk
3. vitelline vessels
All ages referenced to fertilization, not last menstrual period.
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