When you first read this article you have to pinch yourself that it a real true science story and not something out of a fantasy. Growing lentil size “mini-brains” called organoids in Petri dishes sounds extraordinary. These are miniature versions of brains that can be grown for each species. In this experiment it was comparing the growth of the human brain with that of chimpanzees and gorillas because we have bigger brains. Read on.
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Times Newspaper Writer: Rhys Blakely
Cambridge
lab grows small brains to answer the big questions
Thursday March 25 2021, 12.01am, The Times
Lentil-sized “mini brains” grown in Petri dishes have shed
new light on what sets humans apart from the great apes.
By growing miniature versions of the brains of each of the
species, scientists gained a first glimpse of what causes the human brain to
grow much larger than those of chimpanzees and gorillas.
A two-day window, just a few weeks after conception, was
found to be key. The activity of a single gene means that a certain type of
stem cell maintains a cylindrical shape in humans for 48 hours longer than in
our ape cousins. This allows the stem cells to multiply for longer, creating
generations of daughter cells. This delay allows three times as many neurons to
develop in the human brain, compared with that of a chimp.
Madeline Lancaster, of the Medical Research Council
Laboratory of Molecular Biology in Cambridge, who led the study, said: “It’s
remarkable that a relatively simple evolutionary change in cell shape could
have major consequences in brain evolution. I feel like we’ve really learnt
something fundamental about . . . what makes us human.”
The study involved growing miniature versions of brains,
known as organoids, in a lab. During the early stages of brain development,
neurons are made by stem cells called neural progenitors, whose cylindrical
shape makes it easy for them to split into identical daughter cells. The more
times they multiply at this stage, the more neurons the brain will have later.
Eventually the progenitor cells mature, adopt a shape similar
to a stretched ice-cream cone, and stop dividing. In the mini brains, this
shape change took about seven days for human cells and five for the apes. The
extra days appear to help explain our much larger brains.
Researchers then compared which genes were turned on and off. A single gene, ZEB2, was found to be key. When switched off in the gorilla organoids, it slowed the maturation of the progenitor cells, while turning on the gene sooner in human progenitor cells led them to develop more like those in the ape organoids.
For more detail on organoids that can be grown for a variety of body parts not just the brain follow the link below. Remember in vitro means in glass meaning in a laboratory setting. So it is the growing of small organs in a laboratory setting. The small organ being called a organoid.
https://en.wikipedia.org/wiki/Organoid
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