When your heart was just a tube

I've been linking Double X Science a lot lately. That's because they're great. It's rare to get such smart, fascinating, science-centered discussion about female anatomy and reproductive issues that goes beyond the surface dressing we all already kind of know. Case in point: This piece by Emily Willingham about the development of the human heart in utero. You've probably heard at one point or another that a fetus' heart starts beating around 6 weeks (an age which is, by the way, calculated from the date of the mother's last period, NOT from the date of actual conception; so the fetus itself is really only about 4 weeks old at this point, and its mother only missed her period two weeks ago). But what's the heart actually like at that point? Turns out, absolutely nothing like what you imagine. Very cool stuff.


  1. I’d like to point out that a “6-week” fetus is an entity with a continuous existence that dates back to before it’s mother was born.  So while it has only been fertilized for 4 weeks, it is had been alive for longer, most likely between 14 and 50 years (though there could be some outliers).

    1. I’m not sure that you can call a fertilized egg or fetus the same entity as a non-fertilized egg. But this sounds like a good debate for America’s conservative pastors!

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      2. Well, I assume that when the sperm and egg meet God hands out the soul. Unless it’s identical twins, then God doesn’t hand out the souls until it splits.  God, being omniscient, thankfully knows the difference.

        1. You’re ruling out the possibility that one identical twin is always born soulless– the ‘evil twin’ hypothesis.

          1. Aha!  That explains it.  Perhaps it is having a soul that prevents one from growing a dark goatee.

      1. Except the earth was only around for six thousand!


        In all seriousness. An interesting article.

  2. Looks like a slug, but really cool! The heart-cells beating in the petri-dish was awesome looking. Sure, there’s a beating heart tube, but that doesn’t automatically mean a woman loses her right to control what stays in her body……yea. 

  3. My embryology professor used to say that gastrulation was the most important event of your life, going from a single layer of cells into a much more complex animal.  

  4. Saint Louis is riddled with anti-abortion billboards (there are a LOT of Catholics here).  The latest has a cute picture of an obviously highly developed fetus that says “my heart beat 18 days after conception.”

    I knew it was lulz-worthy but now I have a better appreciation for how wrong it is.

    (The other winner?  A local church is having a “The Truth About Dinosaurs!” event complete with bones people can fondle while they’re being made more ignorant than before.)

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