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13.63: Prenatal Development

Last updated

Aug 11, 2023
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- 13.62: Embryo Growth
- 13.64: The Placenta

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f-d_8b871abe806cdc15161f52fe3b07cd62047fc594e6f360c5e97b7bb6+IMAGE_TINY+IMAGE_TINY.jpg

What characterizes this fetus as human?

The human fetus. Notice the details in the face and hands. Compare this to the human embryo, and the amount of growth and development is truly remarkable.

Growth and Development of the Fetus

From the end of the eighth week until birth, the developing human organism is referred to as a fetus. Birth typically occurs at about 38 weeks after fertilization, so the fetal period generally lasts about 30 weeks. During this time, as outlined in Figure below, the organs complete their development. The fetus also grows rapidly in length and weight.

By the 38th week, the fetus is fully developed and ready to be born (see Figure below). A 38-week fetus normally ranges from 36 to 51 centimeters (14–20 inches) in length and weighs between 2.7 and 4.6 kilograms (about 6–10 pounds).

Summary

The fetal stage begins about two months after fertilization and continues until birth.
During this stage, organs continue to develop, and the fetus grows in size.

Review

Make a flow chart of embryonic and fetal development.
Why would an embryo be more susceptible than a fetus to damage by toxins?

Image	Reference	Attributions
	[Figure 1]	Credit: Gray's Anatomy, modified by User:Amada44/Wikimedia Commons Source: commons.wikimedia.org/wiki/File:Placenta.svg License: CC BY-NC
	[Figure 2]	Credit: CK-12 Foundation, using embryo illustrations copyright lelik759, 2014 Source: http://www.shutterstock.com License: Embryo illustrations used under license from Shutterstock.com
	[Figure 3]	Credit: Gray's Anatomy, modified by User:Amada44/Wikimedia Commons Source: commons.wikimedia.org/wiki/File:Placenta.svg License: Public Domain

What characterizes this fetus as human?

Growth and Development of the Fetus

Summary

Review

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