viernes, 2 de diciembre de 2011

FERTILISATION

FERTILISATION occurs when an egg cell and a sperm unite in one of the Fallopian tubes or in the uterus.

This first cell of the new human being has all the DNA of the two parents and is called a zygote. It divides numerous times and forms an embryo. Then the embryo is implanted in the wall of the uterus.

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