Two parallel neural ectoderm progenitors contribute to the developing brain
TL;DR Highlight
Mouse embryo tracing shows front and back of the brain arise from different progenitor cells
Who Should Read
A developer who saw the 'brain is two organs' headline on HN and wonders what the study actually found and whether it's overhyped
Core Mechanics
- Front and back brain start from different cells
- In mouse embryos, the forebrain and midbrain come from Otx2-expressing cells.
- The hindbrain comes from Gbx2-expressing cells, and the two populations never overlap from the earliest stage.
- Chromatin locked in their fates
- Chromatin (the DNA packaging that decides which genes are accessible) differed fundamentally between the two progenitors.
- The researchers say this difference locked each progenitor into its own fate.
- Hindbrain neurons grown in a dish for the first time
- Human pluripotent stem cells (cells that can become any body cell) were turned into functional hindbrain motor neurons.
- They showed action potentials and markers for hindbrain segments controlling facial and swallowing muscles.
- Earlier attempts took the wrong route
- Researchers say past attempts tried to coax forebrain/midbrain progenitors into hindbrain cells.
- This study shows that is not possible.
Community Reactions
- Opinion that the headline is overblown
- A commenter noted the paper's title is about two parallel progenitors contributing to the brain, and it calls the brain a 'composite organ'.
- Another said whether the brain is 1 or 2 organs changes little about how we think of these regions.
- View that the lab method is the real news
- Several commenters said the key point is being able to grow hindbrain cells in vitro.
- They expect this to make ALS-type disease research easier.
- Experience digging into background
- One commenter googled and found the front (sensory)/rear (motor) split in acorn worms was already shown in 2003.
- Their reading is that this study shows the fusion happens only during embryo development in vertebrates.
- Developmental-biology pushback
- One commenter argued the parts don't merge but arise from the same process with different expression driven by signal levels.
- They said calling separate stem cell populations separate organs would make many organs composites.
How to Apply
- Make a habit of checking headline against source
- When a press release goes viral, open the paper abstract first and compare the verbs used.
- Here, put the press release's 'two separate organs' next to the paper's 'postulate composite organ'.
Terminology
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