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Mesoderm: muscle,skeleton,circulatory, excretory systems. gonads, connective tissue, adrenal cortex.

Ectoderm: epidermis, hair, nails, the epithelia of the nose, mouth, and anal canal

Endoderm: epithelial lining of respiratory and digestive tract, pancreas, thyroid, bladder, and distal urinary tracts.

The blastula implants in the endometrial lining and form the placenta (trophoblast (which becomes the placenta)

The chorion contains chorionic villi, which penetrate the endometrium and create the interface between maternal and fetal blood

Before the placenta is established, the embryo is supported by the yolk sac

The allantois is involved in the early fluid exchange between the embryo and the yolk sac

The amnion lies just inside the chorion and produces amniotic fluid

The developing organism is connected to the placenta via the umbilical cord.

Teratogens: are substances that interfere with development

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