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The Primitive Streak

Friday, September 23, 2016 - 02:00 AM

Day12 human embryo, attached in vitro, showing epiblast (green) and structural proteins actin (pink) and tubulin (blue). (Photo Credit: Gist Croft, Cecilia Pelligrini, Ali H. Brivanlou, The Rockefeller University.)

Last May, two research groups announced a breakthrough: they each grew human embryos, in the lab, longer than ever before. In doing so, they witnessed a period of human development no one had ever seen. But in the process, they crashed up against something called the '14-day rule,' a guideline set over 30 years ago that dictates what we do, and possibly how we feel, about human embryos in the lab.

On this episode, join producer Molly Webster as she peers down at our very own origins, and wonders: what do we do now?

This piece was produced by Molly Webster and Annie McEwen, with help from Matt Kielty.

Special thanks goes to the Bioethics Research Library at Georgetown University; Omar Sultan Haque, Kevin Fitzgerald, SJ, and Josephine Johnston; Charlie McCarthy; Elizabeth Lockett, Mark Hill, and Robert Cork; plus, Eric Boodman, Lauren Morello, and Martin Pera.

Producer's note about the image:

Check out the super cool picture that's running with this piece. Scientist Gist Croft sent it to me a couple of weeks after my visit to the Rockefeller lab: it’s an image of the very embryo I looked at under the microscope - a twelve-day old human embryo - but with all the detail highlighted using fluorescent dye. (When I looked in person, we were using a light microscope that showed everything in black and white, with not nearly that precision.) The neon green bits are what's called the epiblast, the clump of cells from which the entire human body develops. See how it looks like it's pulling apart in to two? The scientists don’t know for sure, but they think this embryo might have been on it's way to becoming TWO embryos. Twinning! In action!

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Ali H. Brivanlou, Gist Croft, Cecilia Pelligrini, LeRoy Walters and Magdalena Zernicka-Goetz

Produced by:

Annie McEwen and Molly Webster


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Comments [34]

Dede from mtl

FYI, you ovulate at week 2 of your cycle and "usually" after 2 more weeks, week 4, you get your period. Hence, the embryo is TWO WEEKS, 14 DAYS, when you "miss" your period.

Yes, some people aren't regular and don't realize the're pregnant or tests don't come back positive after a little while longer, but really, normally, the embryo attaches to the utarus wall after 14 days of fertilization. It does't take "WEEKS" to know you're pregnant, it's normally just 2 weeks after ovulation/fertilisation.

Apr. 14 2017 04:55 PM

I can't believe the disparaging comments about Molly Webster. Her enthusiasm is awesome and makes the story much more interesting. Give her more stories to do!

Mar. 13 2017 11:54 AM
Jay from houston, tx

Really Molly Webster? I can't follow you on twitter? I'm disappointed! It would be interesting to know what your thinking when you not thinking carefully.

Oh, and WHAT an amazing story this is. Thank you!

Dec. 13 2016 05:10 PM
Mario from Los Angeles

For those asking how scientists know what happens to a human embryo past 14 days if they've never seen it before these utero images of human embryo development has been available for years. However, these particular images are a breakthrough because the embryo is grown outside the human body past previous biological milestones. Grown in vitro, scientists are able to better remodel these biological milestones by staining and other imaging enhancements.

Dec. 12 2016 01:06 PM

This is the first time I've ever felt uncomfortable about embryo research -- thank you for the thoughtful (and scientific!) episode.

On another note I concur with the criticism of Molly Webster. The "likes" are unprofessional, and her whole "valley girl" approach sounds like I'm listening to a college student doing a class project. This subject -- and Radiolab's audience -- deserve someone who is of higher caliber.

Dec. 10 2016 05:49 PM
Jacq from UK

This is the first time I've listened. I found the episode interesting and engaging, informal but not too simplified. Your voice is fine by the way. Many thanks.

Dec. 10 2016 08:18 AM
David from Toronto

As for Molly Webster's teenage like voice, some will love it, others will hate it. At least she will be appealing to millennials...

You did just fine Molly. Thank you for the Podcast.

Nov. 22 2016 04:53 PM
David from Toronto

How come no mention was made regarding other type of embryos? Have we've been successful going past day 14 with other species? For instance mice, apes, pigs, etc?

Nov. 22 2016 04:50 PM
Eric from Boston from Boston

In contrast to a prior comment, I found Molly Webster to be delightful on air - intelligent, personable, and suffused with the sense of wonder and curiosity that is RadioLab. Great story.

Nov. 14 2016 03:50 PM
John from Cincinnati

Please, please, please get Molly Webster off the air. She may, like, be a fine producer but, like, she is, like, a terrible radio personality. She is, like, obsessed with the word "like" and sounds like a teenager. Like, she used the word "like", like, FOUR TIMES in one sentence in, like, this episode. Like, she's an unprofessional hack in front of, like, the microphone. Keep her in, like, the control booth.

If Jad's leave of absence results in Webster participating in every episode, then I will stop listening until he gets back in January.

Nov. 05 2016 09:34 PM
Susan Erlewine from Athens OH

I just want to say that your guest speaker for this episode seriously misspoke when he characterized Buddhists as believing that life doesn't start until the fetus takes a breath. This is NOT true for many, if not all, Buddhists. I'm a Tibetan Buddhist and our teacher believes that abortion at any time is stopping a life and should not be done if at all possible. Having said that, there is tremendous compassion for those who choose abortion and no judgement. And compassion for the fetus and the doctors, etc. It is all about compassion.

Oct. 31 2016 03:56 PM
Kirk Rose from Alaska

I'm wondering why the study of primate embryos was not discussed. I get that the episode was about the ethics of human embroyos, but there can't be that much difference between the species as we share 99.9% of DNA? And, surely we are able to put aside some of the ethical dilemmas when we move outside our own species, much like the rats referenced in the show? Is there research happening on primate embryos and what can we learn from it?

Oct. 24 2016 11:13 PM
Wes Garwood from Dallas, TX

Thanks Radio Lab for the fascinating program on embryos. As the father of triplets conceived using amazing reproductive technology I encourage everyone to be humbled by what you witnessed in that embryo. I have photos of my children at 8 cells. Those embryos | children are now 19 years old. The inertia of creation that begins at conception creates a life, however dependent on its surroundings, then it's mother, then after birth, the family structure. Please know that in the creation of life at the original conception, we can not cavalierly terminate that life, for that is the life of another human being, however small and undeveloped. My wife and I wrestled with the whole process of IVF as more eggs were fertilized than would be put placed in my wife's womb. The strongest 4 embryos were implanted, the rest remained in the dishes and did not continue to grow. I believe that when I go on to heaven, I will have more children there to greet me, including the 2 that we miscarried (one prior to IVF and the 1 that did not implant and was absorbed). Thanks for listening to my words and I hope that whomever reads these will ponder the nature of life and its Creator.

Oct. 14 2016 01:18 PM
George from Atlanta

I have the same question as Carol. The scientist at the beginning claimed he came up with 14 days based on what he knew about what happens at that date - specifically that it takes shape, among other factors. Well how could he have known that? We are told many times that nobody saw an embryo develop that far until much much later. So something does not add up here.

Oct. 12 2016 12:27 AM

This is the most incredible story! And now I'm obsessed with :)

Oct. 11 2016 05:03 PM
Kelly from Flathead Lake, Montana

Ms Webster. Nice work investigating. Please count how many times you said "like". Please be careful the filler words. Your work is enjoyable however filler words, especially "like" are VERY distracting. When you lessen to this interview you will probably count hundreds of likes.

Problems with "like":
-Dates your age as being a "millennium" (the young people grew up with this being how everyone talks).
- one looses respect in the abilities of the speaker.
If you need help on this, join your local Toastmasters group, its fun and it will help even the most practiced of speakers!
Thank you for your enjoyable and bubbly spirit in your pleasant voice and intelligent contributions!!!

Oct. 10 2016 02:36 PM
Darcy from Irondale, Washington

Great ep as usual, but I want more. I have a 2-year-old, and it wasn't until my pregnancy (my experience and reading) that I realized how entwined my body was with the embryo/fetus. The food I ate taught my baby, before she was even born, what to eat.
She heard our voices, and music, and all of this taught her what was safe, and soothing, and hers.
She learned my gait and my heartbeat from our walks with her inside me, and later she was soothed by the same.
My objection is not with observing embryos but rather with the idea that all of this should lead to artificial wombs.
I am terrified that it would become common, because of how common formula and C-sections have become. We need support for our parenthood, support to nurture our babies ourselves, rather than a culture that tells us none of that is very important, tells us we can just recreate it in a lab.
I get that scientists are hungry to see what happens after 14 days. But, just as observing an animal in its natural environment is worlds above observing it in a zoo, we would learn much more about fetal development if we could observe during pregnancy rather than in a fake womb.
The desire to study the fetus without the mom reminds me of the horrible studies where monkeys were given "mothers" with spikes. I do not suggest that the embryos feel, as the monkeys obviously do (so these studies are not near as abhorrent), but rather that we alreasy know that we have evolved to need our mothers, and we do not need to continue taking mothers away "for science."
Also, a womb is never going to be refrigerated. Why were these embryos?
And (though this may sound hypocritical, as I've birthed a baby), we don't need more people, so talking about putting aborted fetuses in fake wombs??

Oct. 04 2016 07:29 PM
Annya from Maine

A tactless commenter above probably heard the same thing I heard but judged it very differently. Ms. Webster put herself down at least twice, almost certainly more, calling herself a want to be scientist and then commenting that if she touches something she is likely to destroy it. She also talked at great length about what she doesn't know rather than about her curiosity. She is clearly intelligent and versed in science. It's does other women a disservice when we don't own it, when we put ourselves down by the reflexive humble habit that this sexist society teaches us is required of us as women lest we be thought of as vain. Men do not do this and get more respect simply by virtue of acting like they diserve that respect. In my book Ms. Webster has arrived professionally and is working at the best level of science journalism. Own that. It will improve your reporting and put an end to people calling you juvenile.

Oct. 03 2016 07:44 PM
Darik Volpa from Reno

I'd be curious to know if this made the researchers more or less religious or changed their opinions on abortion. Certainly one of the more thought-provoking shows. Nicely done.

Oct. 03 2016 03:04 PM

Lovely scientific research. However it is not at all clear to me why we still pretend embrios have special moral status. As long as they are not "subjects of a life" their moral status depends on the interests of their relatives (if any).
Oh and by the way, Im listening to the program and I'm like... oh my god that´s kwel... duh! Can we quit the idiotic dumb blonde pose please?

Sep. 30 2016 12:33 PM
Navarro from Mexico

I am a chemist, I believe in evolution, I love biological sciences and most Radiolab episodes. I think we humans are persons from the time of conception and listening to this episode made me sick. Especially the joyfulness of the reporter when describing the experiments and the love of the scientist for his research. Could't they make these experiments with animal embrios, even primates? Many times they called the embrios human ("human embrios"), listening to that was like kicks in the stomach to me. This iis an episode I would't listen to again.

Sep. 30 2016 02:08 AM
Marian from New Orleans

I listend to the podcast with excitement, hope and some amount of confusion. I have a number of identities, woman, SF reader, pro-choice, African-American. All of those identities give me questions that you barely touched on in the story. As a speculative fiction reader, I remember many a story that assumed the existence of artificial wombs. I understand that is not possible now, but why is research not being done in that area? Is animal research being done since there is a 14-day limit on human research? It seems to me that artificial wombs would solve both the problem of women who are unable to bring a child to term AND the issue of abortion. If the the pro-life folks insist that a child exists from conception, they can take the 14-day embryo and bring it to term themselves. I mention that I am African American only because I know that minority groups are often the ones experimented on. I don't want to see that. But I don't understand this glow that you seem to want to put around the gestation of a child. Yes, consider the ethics but why consider all of the different religious viewpoints? Someone Catholic may not want this. Someone Buddhist may have no problem at all. Choose a Buddhist test subject after all of the animal testing is done. (And BTW, in Judaism, it is birth/breath--not heart beat as stated in the story.)

Sep. 29 2016 07:39 PM
Alex from Vancouver, BC

After listening to this podcast, I've just been thinking about the 14-day rule, and the sensibility behind whether or not it should be upheld. I'm curious to know what the new guidelines will become in how long embryos will be allowed to be grown in a lab for. I think the reasoning for the original 14 day rule is sound, and also fitting to the 70s where science wasn't yet as advanced as it is today and growing these human embryos. However, my ultimate thought/question is this: If we allow first trimester abortions (1 to 12 weeks of pregnancy), and in some cases abortions until the age of viability of a fetus (about 23 weeks now with our advanced life saving technology of extremely premature neonates), then why would we not let labs grow embryos/fetuses until 12 weeks of age....

If not, then we are saying that fetuses in a woman's body hold more value than a fetus grown in a lab, but in fact these are genetically the same beings with the same potentials and so should be treated equally.

Just my opinion!

Sep. 29 2016 07:28 PM
Adrian Menichelli from Saddle Brook, NJ

I love this show, this one specially touch me. The way everybody speak so respectfully about the embryos, how passionate they are in pushing the boundaries is really incredible. The last question was incredible . . . Indians think that this life is just part of the circle . . . .
Great!!! I love this show!!!

Sep. 27 2016 10:09 AM
John from USA

Why does Molly Webster have to talk like a damn teenager all the time?

Sep. 26 2016 04:35 PM
Arie from Indonesia

this episode has brought tears to my eyes. Well done, Radiolab! Now off to share this on Facebook!

Sep. 26 2016 09:30 AM
William from North Carolina

I really love this show.

Sep. 25 2016 01:37 PM

Ali is incorrect -- the Jewish view is that life begins at first breath, since G-d breathed life into Adam. I don't know anything about Islam, but Ali is wrong in stating that in Jewish tradition life begins at first heartbeat.

Sep. 24 2016 07:14 PM
RS from Washington DC

I am going to ask what will probably be considered a radical idea. While at first I was inclined to accept the fear of what happens when human beings learn how to "manufacture" babies from embryos - and thereby also inclined to accept this notion of stopping "experiments" at 14 days - I must ask this; For women who are constantly fighting to have autonomy over their own bodies and choices regarding reproductive rights, would it not be an EXCELLENT thing for us to be able to learn how to grow an embryo into a baby without the presence of maternal input? Rather than forcing women to carry something to term that they don't want, or the alternative of ending that potential life through abortions, we could offer women a third choice - the choice to extract the embryo so it can be given to the people who do want it to grow into a fetus and eventually into a baby.

It seems like a win/win choice (depending on the procedure that would allow this to happen). Win #1: A woman is not obligated to sacrifice her body in order to gestate a fetus for nine months if she doesn't want to. Knowing how to fabricate a baby from an embryo is even better for those women who want to have a baby but could die or risk their own life in the process of giving birth. Perhaps we could even learn how to allow a man to be host to this embryo, growing their fetus to a baby within themselves. Win #2: Everyone who holds the embryo's right to potential life above a mother's right to make choices affecting her own body can forever hold their peace.

Sep. 24 2016 01:48 PM
carol from Seattle

If never seen before, how did the original scientist/ethisist who decided 14 days know what happened up to 14th day? Know what was going on in embryo--divided, twins, united, etc

Sep. 23 2016 10:50 PM
Clayton from Illinois

It's amazing that we can see these things. I want more pictures.

Sep. 23 2016 07:48 PM
DMol from Rainy British Columbia

Haven't listened to it yet (can't wait), but saddened again by the shorter length. We user to get Episodes at least 10 minutes longer (or more)... and any additional time spent listening to RadioLab is time well spent.

Sep. 23 2016 05:00 PM
Sung from Minneapolis

Animal embryos are grown well past 14 days in the lab. Animal embryos have epiblast. I don't get why this experiment is suggested to be a huge discovery. Had this episode suggested any human-species-specific findings in embryo development that I didn't catch? Thanks for the show.

Sep. 23 2016 09:53 AM
Dinah from Washington DC

I just listened to this episode this morning - it was AMAZING - one of your best so far - and that's a high bar. This is mind-blowing science explained for the lay person like me who is curious about the origins of life. Thanks so much!

Sep. 23 2016 09:18 AM

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