This animation shows the process of conception in which a sperm unites with an egg cell to form a fertilized egg.
During intercourse, sperm are released into the vagina near the cervix, swim through the uterus and travel up the fallopian tubes. Sperm are composed of 3 parts: a head, a middle section, and a tail. The tail propels the sperm, which is powered by energy cells stored in the middle section. The head of the sperm contains the man' s genetic material and an enzyme-filled cap needed to help the sperm penetrate through the outer membrane of the egg.
As an egg released by an ovary travels through a fallopian tube, it may encounter hundreds of sperm that have survived to reach this point in their journey. Eventually, one sperm may succeed in breaking through the egg' s outer membrane.
After penetrating the egg' s outer membrane, the sperm releases its nucleus, which unites with the nucleus from the egg. Fertilization or conception occurs when the sperm fuses with the egg to form a fertilized egg (zygote).
Reviewed last on: 9/16/2008
Dan Sacks MD, FACOG, Obstetrics & Gynecology in Private Practice, West Palm Beach, FL. Review provided by VeriMed Healthcare Network.