250 million sperm enter the vagina, 99 percent of them die off within 30 minutes of entering the vagina.
All the remaining sperm that yet are still alive must navigate there way through the cervix located at the far end of the vagina
The sperm is attacked by Leukocytes a leukocyte is a white blood cell that is launched by the body's immune system
The Utero-tubal Junction is the doorway to the Fallopian tube kinda like a water slide but in order for the sperm to pass through they must display the right molecular characteristics to pass through to fertilization
The sperm that is alive and thriving must attempt to find egg at the end of upper Fallopian tube egg releases chemicals that sperm can sense and they begin to move more quickly. The sperm that contacts with the "Outer Coat" of the egg has a bag of enzymes on its head that explodes.
The zygote travels down the Fallopian tubes towards the uterus,cells begin dividing. On day four the tiny bundle of cells is named a blastocyst