Figure 34 Fertilization

Fertilization occurs within fallopian tube _16—

Enlarged view

Illustration copyright © Nucleus Medical Art, all rights reserved, nucleusinc.com.

Fertilization occurs within fallopian tube _16—

Enlarged view

Illustration copyright © Nucleus Medical Art, all rights reserved, nucleusinc.com.

• Several sperm fuse with the zona pellucida, but only one sperm successfully penetrates the egg.

• The successful sperm sheds its body and tail so that only the head (containing the genetic material) actually enters the egg.

• When fertilization occurs, the newly fertilized egg starts to grow and develop into an embryo.

• The embryo is propelled by the fallopian tube and begins its three- to four-day journey into the uterus.

• Approximately two days after reaching the uterus, the developing embryo has about 100 cells. These cells then burrow their way and implant into the lining of the uterine wall.

• A portion of the developing embryo makes contact with the mother's circulatory system and becomes the beginning of the placenta. The placenta will provide the embryo with a source for growth and nourishment.

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