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The Endowment for Human Development
The Endowment for Human Development
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Multilingual Illustrated DVD [Tutorial]

The Biology of Prenatal Development

Introducing the Multilingual Illustrated DVD
Explore the fascinating imagery and facts presented in The Biology of Prenatal Development at your own pace. Each clip from the program is accompanied by its corresponding written script. Select Play Movie to watch any clip. Select See Snapshots to view high resolution images. See the program script and subtitles in 88 languages by using the Choose Language drop-down menu and clicking Refresh. Subtitles are displayed in your chosen language and may be turned on and off by clicking the button found in the lower right corner of the movie player. A "full screen" option is also available by clicking the button.

National Geographic Society This program is distributed in the U.S. and Canada by National Geographic and EHD. [learn more]

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The 8-Week Embryo

Chapter 30   8 Weeks: Brain Development

At 8 weeks the brain is highly complex and constitutes almost half of the embryo's total body weight.

Growth continues at an extraordinary rate.

Chapter 31   Right- and Left-Handedness

By 8 weeks, 75% of embryos exhibit right-hand dominance. The remainder is equally divided between left-handed dominance and no preference. This is the earliest evidence of right- or left-handed behavior.

Chapter 32   Rolling Over

Pediatric textbooks describe the ability to "roll over" as appearing 10 to 20 weeks after birth. However, this impressive coordination is displayed much earlier in the low-gravity environment of the fluid-filled amniotic sac. Only the lack of strength required to overcome the higher gravitational force outside the uterus prevents newborns from rolling over.

The embryo is becoming more physically active during this time.

Motions may be slow or rapid, single or repetitive, spontaneous or reflexive.

Head rotation, neck extension, and hand-to-face contact occur more often.

Touching the embryo elicits squinting, jaw movement, grasping motions, and toe pointing.

Chapter 33   Eyelid Fusion

Between 7 and 8 weeks, the upper and lower eyelids rapidly grow over the eyes and partially fuse together.

Chapter 34   "Breathing" Motion and Urination

Although there is no air in the uterus, the embryo displays intermittent breathing motions by 8 weeks.

By this time, kidneys produce urine which is released into the amniotic fluid.

In male embryos, the developing testes begin to produce and release testosterone.

Chapter 35   The Limbs and Skin

The bones, joints, muscles, nerves, and blood vessels of the limbs closely resemble those in adults.

By 8 weeks the epidermis, or outer skin, becomes a multi-layered membrane, losing much of its transparency.

Eyebrows grow as hair appears around the mouth.

Chapter 36   Summary of the First 8 Weeks

Eight weeks marks the end of the embryonic period.

During this time, the human embryo has grown from a single cell into the nearly 1 billion cells which form over 4,000 distinct anatomic structures.

The embryo now possesses more than 90% of the structures found in adults.

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