Source: Yolk Sac image 1, Public Domain: http://en.wikipedia.org/wiki/File:Gray22.png; Yolk Sac image 2, Public Domain: http://en.wikipedia.org/wiki/File:Gray23.png; Gray's Placenta image, Public Domain: http://en.wikipedia.org/wiki/File:Gray39.png
A sac-like structure that gives rise to umbilical blood vessels.
A sac that encloses the embryo and is filled with amniotic fluid that cushions and protects the embryo.
An outer membrane around the fetus that protects the fetus, absorbs blood from the mother to be transferred to the embryo, and secretes HCG to prevent endometrial breakdown.
The structure that develops from the outer cell layer of the blastocyst, the placenta provides blood flow, oxygen, and nutrients to the developing child while carrying away waste products.
The cord that connects the embryo to the placenta, the umbilical cord carries nutrients to the child and wastes away.
A membranous sac attached to the embryo that provides early nourishment and develops the cardiovascular system and germ cells; the yolk sac eventually disintegrates.