[mommyshoppinghabit]

I know in the earliest weeks the embryo is sustained by it, not necessarily by what you eat, which is a relief b/c I am eating sooo badly b/c of nausea. It seems that the more natural the food, the more I'm repulsed by it. And the more processed the food, the more I crave it which is not how I usually eat.

 

[lyttlewon]

I wasn't aware there was a yolk sac. It sounds like four to seven weeks is the length of time it lasts.

Quote:

At the end of the fourth week the yolk-sac presents the appearance of a small pear-shaped vesicle (umbilical vesicle) opening into the digestive tube by a long narrow tube, the vitelline duct. The vesicle can be seen in the after-birth as a small, somewhat oval-shaped body whose diameter varies from 1 mm. to 5 mm.; it is situated between the amnion and the chorion and may lie on or at a varying distance from the placenta. As a rule the duct undergoes complete obliteration during the seventh week, but in about three per cent. of cases its proximal part persists as a diverticulum from the small intestine,