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  • “I think I was in sixth grade

  • Fifth grade

  • Seventh or eighth grade

  • High school

  • High school, but that feels late to me.”

  • I asked a bunch of my coworkers when they first had the talk.

  • Not like the sex talk, but the talk about how babies get made from a scientific perspective.

  • Honestly, for someone who just successfully gestated and delivered a human baby, I know

  • an embarrassingly little amount of, like, how my egg was fertilized.”

  • Even if we don't remember it super well, we were likely taught it. So...how does fertilization work?

  • Oh, God, okay

  • ummm....

  • So, sex happens

  • After the ejaculation happens

  • The little sperm swimmers kind of like to do, do do, do do like

  • Many, numerous sperm

  • It's a bunch of them swimming up there

  • They're like going really fast

  • Um

  • There are so many that are, like, looking for the egg

  • It's weird because I feel like you don't really hear about the egg.”

  • The egg is very passive and just like 'Ehhh, fertilize me.' And like the sperm is like

  • the one doing all the work.”

  • Everyone I talked to told me similar stories that all had a lot of holes.

  • And it might be because of what's inside these.

  • Right, so it's all been modeled off this fairy tale where you have the knight in shining armor

  • going to save the damsel in distress.

  • I think most of us have heard some version of that story. And it's just... it's not true.

  • It's not factual.

  • Nadia Johnson and Lisa Campo-Engelstein co-wrote a paper about how the fertilization story

  • we're taught often centers on the male perspective.

  • In it, they analyzed popular textbooks used from middle school to medical schoolkeeping

  • an eye out for gender-biased language.

  • I ordered some of them on eBay.

  • This book describes only the sperm's role in fertilization:

  • “300 million sperm are released...some are attacked...and many simply die along the way.

  • Only one sperm can fertilize an egg.”

  • In other textbooks, the female body's role is described using only passive language:

  • If an egg is present, there's a good chance of it being fertilized.”

  • OrIf an ovum is present, the sperm swarm around it and penetrate those layers.”

  • The books show the sperm actively swimming, surviving, and penetrating while the egg just...sits

  • there.

  • It's sending these really problematic messages about what it means to be male and female

  • and who has agency and who is passive.

  • The truth is, fertilization involves two equally important reproductive systems collaborating

  • in an awesome two-player adventure.

  • Real quick before we start: There are different ways of making babies for different types

  • of people.

  • In this video, we'll be focusing on the fertilization story between male and female

  • reproductive organs.

  • That story starts with the egg's journey, beginning in the ovaries.

  • Once a month, during ovulation, a mature egg bursts out of the ovary.

  • A finger-like membrane at the end of the fallopian tubes scoops that egg up.

  • And other membranes pull it toward the uterus.

  • It's a complicated, necessary trip.

  • And for the best chance of fertilization, millions

  • of sperm enter the vaginal canal around the same time.

  • Some go in the complete wrong direction, and it's game for them over early on.

  • The ones that go in the right direction encounter

  • a more acidic environment than they're used to.

  • That acidity in the vaginal canal can harm a few sperm, but the seminal fluid they're

  • ejaculated in acts as a sort of shield potion, protecting them.

  • And while some textbooks describe parts of the female reproductive tract as a place that

  • sperm never make it out of, or are attacked by...

  • They don't talk about the ways in which the female body actually helps.

  • After the sperm travel through the vaginal canal, they enter the cervix.

  • The environment of the cervix can be really helpful.

  • It enables the sperm to survive for a little bit longer

  • and then it facilitates the migration of sperm.

  • Then sperm swim rigorously towards the egg, but...let's just say that they're not

  • Michael Phelps.

  • It has this tail and you think, oh, this tail must be responsible for it swimming from

  • the cervix basically to the egg.

  • We know now that most of the motility is because of the things that the uterus and the female

  • reproductive tract is doing to move the sperm along.

  • First, during ovulation, the thickness of the fluid in the cervical canal is thinned

  • out.

  • Then, the muscles of the uterus contract, propelling the sperm faster than they could

  • ever swim, toward the fallopian tubes.

  • At the same time, the egg is releasing a chemical signal that acts almost like a GPS, so that

  • the sperm have a good indicator of which fallopian tube to go to.

  • There, the egg and the sperm are almost within reach of each other.

  • The female reproductive tract releases a cocktail of protein and calcium, which gives the sperm

  • the strength to beat their tails harder and swim faster than they did before.

  • This fluid also helps the sperm weather away this little cap.

  • And once it's gone, they secrete enzymes that help it dig through the two layers of

  • the egg's protective outer shell.

  • I feel like every text we looked at had the word penetrate.

  • We think of the word penetrate as neutral, but think about when we use that language

  • of penetrate.

  • We talk about forces penetrating army lines and we think about war. Penetrate is this

  • language of like an assault, of doing harm.

  • Penetrate is not a friendly, like, welcome in.

  • The egg doesn't just wait around to see which sperm will break through:

  • It uses chemicals to select the best sperm, the one that will produce the healthiest offspring.

  • And its work doesn't just stop there.

  • Once the egg and the sperm come together, the selected sperm deposits its genetic information.

  • The egg essentially self destructs all of its other sperm receptors to make sure no

  • other candidates can get it.

  • And it combines with the egg to start forming what will soon be an embryo.

  • And that is how fertilization really happens.

  • This idea of who decides and who the experts are in the field...in science it's been white

  • men for a very long time.

  • Like the first person who ever saw sperm under a microscope scope was a man. And he had assumptions

  • about what it was.

  • If the assumption is that the sperm is the most important part of the whole puzzle, it's

  • not like that's going to necessarily be challenged if all the people at the table are men.

  • 80% of the textbooks Lisa and Nadia analyzed had descriptions that were at least somewhat

  • gender-biased.

  • It can be done. It can be explained in a fact based, unbiased way. But it isn't always.

  • What we're talking about is not just changing language in a textbook.

  • What we're also talking about is systems that are in place and have been in place for a

  • very long time.

“I think I was in sixth grade

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B2 US Vox sperm egg fertilization penetrate female

How sperm got all the credit in the fertilization story

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    joey joey posted on 2021/07/08
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