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National Geographic Society Este programa se distribuye en los Estados Unidos y Canadá por National Geographic y EHD. [obtenga más información]

DVD ilustrado plurilingüe

La biología del desarrollo prenatal




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Capítulo 1   Introducción

The dynamic process by which the single-cell human zygote becomes a 100-trillion-cell adult is perhaps the most remarkable phenomenon in all of nature.

Researchers now know that many of the routine functions performed by the adult body become established during pregnancy - often long before birth.

The developmental period before birth is increasingly understood as a time of preparation during which the developing human acquires the many structures, and practices the many skills, needed for survival after birth.

Capítulo 2   Terminología

Pregnancy in humans normally lasts approximately 38 weeks as measured from the time of fertilization, or conception, until birth.

During the first 8 weeks following fertilization, the developing human is called an embryo, which means "growing within." This time, called the embryonic period, is characterized by the formation of most major body systems.

From the completion of 8 weeks until the end of pregnancy, "the developing human is called a fetus," which means "unborn offspring." During this time, called the fetal period, the body grows larger and its systems begin to function.

All embryonic and fetal ages in this program refer to the time since fertilization.