Dr. Sergiu Pașcă

But they change a lot during development.

They're made out of different units, and the units change.

And it was very well known that during early development, so prenatal, before birth, you primarily have two B subunits.

And then after birth, they're primarily 2A.

So if you look in brain development, you just see how essentially 2B goes up and then it goes down and 2A goes up.

And when you look, they meet around birth.

So very often people thought that it's birth itself that triggers that switch.

That canonical, it's called a canonical switch because we all thought that it was like so classic.

And then you take an organoid that you maintain in the dish for 600 days.

And of course, we're not inducing birth.

We're not changing media.

We're not doing anything special.

And no hormones from mom.

No hormones changes.

Like, you know, we keep exactly the same media, which is certainly a very simplistic, you know, kind of like soup of chemicals, but we don't change it.

And then you just look at this two subunits and you see how like 2B goes down and 2A goes up and they pretty much meet that nine months of keeping them in a dish.

So that tells us that there's some sort of intrinsic clock.

Once you start a development,

the cells measure really, really well the time of development.

That does not mean that all aspects of development are going to now be recapitulated in a dish, but it tells us that there is this incredible ability of cells, especially in the nervous system, because of course those cells will keep for the rest of our lives.