What you’re seeing here is a human embryo, about one day after fertilization.
Every one of us started out this way,
从一个细胞分裂成两个 三个 很多个细胞
as a single cell dividing into two cells, then three, four,
and more. But it takes nature a lot of trial and error
to go from this… to this.
Only a few embryos, about one in three,
have a genetic makeup that’s good enough
to let them to grow into a baby.
Scientists don’t know why,
而这使得人类的繁衍率 相较于其他哺乳动物 非常低下
but we humans are some of the least fertile mammals around.
Not long ago, when Stanford University scientists
made this time-lapse video of developing embryos,
they noticed something no one had ever seen before.
Up til then, researchers thought that embryos
could grow at many different rates and still be healthy.
But they discovered that viable embryos actually follow a pattern,
a precise embryonic clock.
This has huge implications for patients going through in vitro fertilization,
for whom each embryo, carefully cultivated in the lab
before it’s transferred into a woman, is an embodiment of hope.
For patients like Laura and Alex Ibanez
the question is: Which of their embryos can become a baby?
The stakes are high: transfer too many healthy embryos
and you could end up with a risky twin or triplet pregnancy.
Transfer too few and patients might not have a baby at all.
So what if embryologists could make more accurate predictions?
A company in Menlo Park wants to make that possible.
They film the embryos with a tiny camera inside the incubator.
A computer algorithm automatically tracks
the development of each embryo.
A new ring means the computer has picked up on a new cell division.
Embryos that go from two to three cells in 9 to 11 hours,
and then from three to four cells in under two hours
have the best chance of making it to day five – a critical milestone.
Because on Day 5, the embryo gets ready to break out of its shell
and attach to the uterus.
This test was cleared by the FDA last year.
Today it’s in more than 30 clinics.
You often hear life described as a miracle.
And it seems even more wondrous, now that we’ve coaxed nature
into revealing some of its secrets,
to give us a glimpse into how it all begins.