An introduction to human fertilization and the challenges facing the sperm and egg. How do they find each other and how do they combine to form a new life?
- When an egg is released from the ovary, it travels down the fallopian tube to await the sperm.
- Before sperm can enter an egg, it must become hyperactivated.
- Once a sperm has entered, the egg hardens to prevent other sperm from getting in.
- Inside a fertilized egg, genetic information gathers to form a zygote.
Once a month a woman's egg is released and travels down the fallopian tube, and ends up in the correct position to be fertilized.
And, once released, the egg has only 24 hours before it disintegrates.
So the pressure's on for the egg and the sperm to be in the right place... at the right time.
The egg leaves the ovary... and travels down the fallopian tube, where it waits for the sperm to arrive.
It's here, at the opening of the tube near the uterus, where the sperm and the egg combine.
But before the sperm can enter the egg... it must become hyperactivated.
This process takes several hours and changes the composition of the sperm. Once complete, the sperm then releases an enzyme that breaks down the egg's outer layer.
The sperm discards its tail and the egg hardens to prevent any other sperm from getting in.
Inside the egg the genetic information is gathered in two tiny balls.
Details from the mother in one... and details from the father in the other.
These combine to form a zygote.
The unique genetic makeup of the offspring is now determined... deciding everything from eye color, to chance of heart disease... even personality.