The Journey of the Sperm: By Kayla Doucette and Serena Tura
I'm so excited to finally meet my friend!
Finding Directions (Cervix)
Which way do I go again????
Getting pulled over on the Highway (Uterus/White Blood Cells)
I hope my friend doesn't get arrested.
Approximately 250 sperm enter the vagina, most of them die (99%) within 30 minutes. The sperm are destroyed by deadly acids that protect the vagina from pathogens.
Entering the Neighborhood (Uterotubal Junction)
Found the right neighborhood, now I just need the house!
60,000 remaining sperm navigate through the cervix located at the far end of the vagina. The cervix is usually plugged shut with mucus, but during ovulation estrogen flows to the uterus and softens the mucus so sperm can make their way through. Most sperm will die or get lost in the thousands of passageways in the cervical canal.
Finding her House (Fallopian Tubes)
Which house was it again?
The approximately 3,000 remaining sperm must navigate through the uterus to the fallopian tubes. Muscular contractions help guide the sperm to the correct fallopian tube, while leukocytes (white blood cells) attack the sperm.
Finally Meeting (Fertilization/Implantation)
I'm so glad we finally got to meet Fletcher!
Sperm must show the proper swimming characteristics and display the correct molecular recognition to pass through the Uterotubal junction, which is the doorway to ther fallopian tube.
In the fallopian tube, approximately 10-30 sperm remain and once they are in there, they are safe from leukocytes. Sperm are provided with nourishment from the fallopian tube so they can stay alive for h=several hours or even days.
The remaining sperm attempt to find the egg at the fallopian tube, while the egg releases chemicals so the sperm move more quickly and the sperm shed layers of protein to be able to propel faster. The sperm makes contact with the outer shell and the egg allows the sperm to enter and the 23 individual chromosomes of the sperm and egg begin to pair up. The zygote(union of sperm and egg) then travels towards the uterus and begins cell division.