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Two parallel neural ectoderm progenitors contribute to the developing brain

664 points · 258 comments · emigre

  1. bethekind · · focus · HN ↗
    > They identified two different brain progenitor cells. One, which expresses a gene called Otx2, is destined to become the forebrain and midbrain. The other, which expresses a gene called Gbx2, is committed to forming the hindbrain. They showed that these two cell populations never overlap; they are mutually exclusive from the earliest stages of development.

    Very cool. Never thought the brain could have two completely different ancestors

    1. trhway · · focus · HN ↗
      and from another post on the front page right now <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=49735541">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=49735541 :

      &quot;Nervous systems are typically defined as networks of neurons that communicate across synapses. But Burkhardt’s lab found something unique in ctenophores: Beneath the animal’s outer surface is a nerve net (pink mesh in this 3D reconstruction) whose neurons are connected by continuous cytoplasm — but with no synapses between them. “I don’t think any other animal has a nervous system like that,” Burkhardt said. Because ctenophores are one of the earliest branches of the animal family tree, the finding indicates that evolution may have crafted nervous systems twice: in ctenophores, and separately in jellyfish and all other animals.&quot;

      1. ozim · · focus · HN ↗
        Funny thing when reading that is as a human I read „crafted nervous system twice” like it would be done over a week or two.

        We fail to imagine how much time takes to „craft a nervous system”.

        Super scary how small are we in big scheme of things.

        1. stymaar · · focus · HN ↗
          I think the fact that the sentence says we share the nervous system with jellyfish gives a good indication of that.
        2. cmrx64 · · focus · HN ↗
          <a href="https:&#x2F;&#x2F;learn.genetics.utah.edu&#x2F;content&#x2F;senses&#x2F;eye&#x2F;" rel="nofollow">https:&#x2F;&#x2F;learn.genetics.utah.edu&#x2F;content&#x2F;senses&#x2F;eye&#x2F;

          at one point I learned that it would only take a few hundred thousand years to evolve an eye, and time felt much deeper.

    2. kazinator · · focus · HN ↗
      Fun fact: the hindbrain progenitor cell is shaped like a little lizard.
      1. akk0 · · focus · HN ↗
        The lizard brain, not because it resembles the brain of a lizard, but because it&#x27;s made up of a trillion tiny lizards
        1. TeMPOraL · · focus · HN ↗
          I bet you can tune hyperparameters on the MRI so that the resulting image makes the lizard brain look like a lizard, too.
        2. machomaster · · focus · HN ↗
          Because they are proudly causing animalistic, degenerate behavior like Lizzo.
      2. computerdork · · focus · HN ↗
        Like the thought:) But actually have read that the hypothesis that the hindbrain (or lower brain) had evolved directly from our lizard ancestors while the upper brain (which does more complex types of thought) evolved later turned out to be wrong. Like the study has shown, they evolved at the same time, and many animals had both. It&#x27;s just in humans, the upper brain evolved much larger in proportion to the lower brain.

        <a href="https:&#x2F;&#x2F;thebrainscientist.com&#x2F;2018&#x2F;04&#x2F;11&#x2F;you-dont-have-a-lizard-brain&#x2F;" rel="nofollow">https:&#x2F;&#x2F;thebrainscientist.com&#x2F;2018&#x2F;04&#x2F;11&#x2F;you-dont-have-a-liz...

        But yeah, evolution is fascinating.

    3. avadodin · · focus · HN ↗
      Why would it be surprising?

      All parts of the body are built like this. Otherwise we would be blobs.

      Before becoming two parts they probably were part of the same parent protobrain tissue.

      If you told me the hindbrain was ectoderm-derived but the forebrain was endoderm-derived, I might raise an eyebrow or two.

      1. mcherm · · focus · HN ↗
        &gt; All parts of the body are built like this.

        Please name one other organ that arises from two separate progenitor cell types. If this is common, I have never heard of it.

        1. MarkusQ · · focus · HN ↗
          Well, your heart contains both mesoderm derived cells (enervation) and ectoderm derived cells (musculature).
        2. pixl97 · · focus · HN ↗
          Bones, guts, many glands, kidneys.
      2. bobmcnamara · · focus · HN ↗
        &gt; Before becoming two parts they probably were part of the same parent protobrain tissue.

        Article says they weren&#x27;t.

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