Let's swim single file! It's gonna be a tight fit!!
The egg is this way!
Umm, a little help?!?
No it's this way!
About 250 million sperm enter the vagina after intercourse. Within 30 minutes 99% of them are wiped out by the acidic environment.
I'm gonna get there first!
No I am!!
The 600,000 remaining sperm must navigate the cervix. They have to swim single file in order to fit through the small opening, and many will die in the numerous dead ends.
Finally! You made it!
3000 sperm are left and must navigate the uterus and enter the correct fallopian tube. On their way they will be attacked by Leukocytes sent by the immune system. Many sperm will go down the wrong tube.
About 10-30 sperm remain. Now in the fallopian tube they are safe from the Leukocytes are provided nourishment by the tube. Now it's just a matter of getting to the egg.
Almost there! Wow, it is nice in here.
At last a sperm has made it to the egg. The sperm and the egg will combine their chromosomes and create a zygote. Once a sperm makes it, the other sperm are unable to get to the egg.
Alright! Now, let's combine.
Over the next few days the cell will start dividing and eventually make its way through the fallopian tube and implant in the wall of the uterus, where it will develop into a new human.