Building a baby: The first two weeks

this is how a human gets made every one of us started out this way with a pretty good idea what happens over the nine months it takes to produce a newborn but there's this one bit that's been missing right at the beginning before this animation even starts the very first few weeks now armed with new ways of growing human embryos in the lab scientists are learning what the very beginning of human development looks like [Music] for decades studying this crucial early time in a human embryos development was a technical headache embryos are hard to get and keep alive outside the body and it's an ethical challenge guidelines put together in the late 70s and 80s prevent scientists from growing embryos for longer than 14 days despite the hurdles scientists do know a bit about what happens in those critical weeks often from animal studies or rare human tissue samples they know that sperm fertilizes egg and one cell grows to two four eight and so on around day five or six the blob starts to feature different types of cell scientists call this blob a blastocyst all being well the cells in the blastocyst begin to differentiate one weekend it implants into the wall of the uterus what happens next has been a bit of a mystery by implanting itself into the wombs wall the embryo basically hides and that makes studying it in humans impossible one way of exploring this crucial time is to study embryos donated by people who no longer need them for fertility treatment in the last few years several labs have developed new ways to nurture these embryos their techniques have allowed them to start building a picture of human development that's more detailed than ever before here's a day6 embryo growing in a lab cells destined to become the actual fetus attacked in green those that go on to form the placenta in blue by day eight the cells are sourcing and arranging themselves the green fetal cells have condensed together and in red here are cells that will form the interface between the baby and the placenta it seems these extra embryonic structures develop a little later in humans than expected from studies in other animals day ten the whole thing increases in size and bundles of cells start developing into support structures surprisingly at this stage the embryo can direct its own development with no input from the mother's tissues by day 12 the outskirts of the embryo are preparing to bind more strongly to the wall of the uterus after all if this were a natural pregnancy the embryo would be there for the next nine months you can even see little holes appearing ready for the mother's blood vessels to start supplying the embryo with essential oxygen and nutrients by now the embryo is signaling its presence to the mother via a hormone the one that pregnancy tests pick up HCG labeled here in yellow after two weeks the team's ended their experiments in line with the ethical 14-day limit to study what happens after 14 days researchers had to turn to different techniques recently scientists have built artificial embryo like structures from stem cells using these partial models they can study things like cell signaling or even the formation of the primitive streak the crucial thread of cells which guides a process called gastrulation that's the moment the embryo decides which end will become the head here they use human stem cells growing in an animal embryo to explore that process but even after this early phase is over there is still a lot of work involved in building a body to study later phases scientists have made and analyzed high-resolution 3d atlases of human embryos and fetuses one team found that the left and right hands don't simply mirror each other when growing their nerves instead some branches take random paths in each limb another group saw muscles that grew in early embryos only to disappear as the fetus developed like these as yet they're not sure why it's becoming ever clearer just how important to human embryos first few weeks are many scientists hope that more research will lead to a better grasp of why some pregnancies fail and how birth defects arise maybe even make in vitro fertilization work better but some just want to understand exactly what happens to this tiny ball of cells in this short spark of time at the beginning of all of us [Music]

Channel: nature video

Views: 5,866,692

Rating: 4.7150435 out of 5

Keywords: science, nature video, embryo, baby, development, brivanlou, gist, croft, placenta, yolk, amniotic sack, rockafeller, foetus, fetus, embryoid, stem cell, transparent embryo, pregnancy

Id: 9AX1XwKCYQE

Length: 5min 37sec (337 seconds)

Published: Wed Jul 04 2018

Reddit Comments

[u/[deleted]]

I can't wait for this topic to be researched more, it's still so elusive.

[u/Maxwelljames]

Hey! Just like my song!

https://soundcloud.com/neil-bobenhouse/building-a-baby