Building a baby: The first two weeks

Building a baby: The first two weeks

This is how a human gets made. Every one of us started out this way. We have a pretty good idea what happens over the 9 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. For decades, studying this crucial, early time in a human embryo’s 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 fertilises egg, and one cell grows to two, four, eight, and so on. Around day 5 or 6, 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 week in, it implants into the wall of the uterus. What happens next has been a bit of a mystery: by implanting itself into the womb’s 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 day 6 embryo growing in a lab. Cells destined to become the actual fetus are tagged in green, those that go on to form the placenta in blue. By day 8 the cells are sorting and arranging themselves – the green fetal cells have condensed together, and in red here are the 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 10. 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 9 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 signalling its presence to the mother via a hormone – the one that pregnancy tests pick up – HCG – labelled here in yellow. After two weeks, the teams 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 signalling, or even the formation of the primitive streak – the crucial thread of cells which guides the 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 analysed high-resolution, 3D atlases of human embryos and fetuses. One team found that the left and rights 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 a human embryo’s 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 fertilisation 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.

100 thoughts on “Building a baby: The first two weeks

  • Abortion in the first 5to 6 Weeks of pregnancy is reasonable to do afterwards it is questionable more than 10 to 12 weeks it should be criminalised

  • I'm Pro-Life, so I'll do everything in my power to protect that baby while it's in the womb. But after it's born, it better damn well get a job, because I'm not going to support it with MY tax dollars!

  • Not even sure why it's in my recommendation..but I'm not complaining .. it brought butterflies to my heart and I cannot wait for the blessing of my own one day.

  • Why is it only legal to grow an embryo for scientific purposes for up to 14 days when abortion is legal far beyond that??

  • I had an amazing, life-changing 16-day pregnancy last year. 4 weeks, 2 days "gestational age." Around 7 DPO, someone was 'with' me in a spiritual or metaphysical sense (I'm not religious.) I've never been so awed or humbled in all my life! I had implantation cramping, I was boiling, I suffered the worst headache ever, I enjoyed the only real nap I've had as an adult, my navel started to turn brown, my breasts shrunk. In the last few days, I could feel my womb bouncing inside of me as I walked along downtown LA's sidewalks. Later, I grew montgomery tubercules and my nails were longer than they'd been in 20 years.

    I buried the unexpected pieces of decidua that I birthed in a houseplant grave. I decorated it with cute figurines and painted "Briefly" on the side of the pot. It makes me smile.
    I love my gastrula!!!

  • The Quran already addressed this before modern science was able to decipher this information 😌 so glad i believe in the true way of life. God is the greatest.

  • After 14 days, this experiment and learning stops for ethical reasons. I can figure out what those ethical reasons may be. Either scientists know what happens, or they don't at this stage in the embryo, and I'm guessing that to go further would find that it constitutes life, thus stopping that experiment after 14 days would be considered killing life ! ? This video shares great scientific knowledge. I would like to know more about why this 14 day limit is not to be breached. That might help answer many questions for many.

  • i felt bad for these embryos (soon to be human if there's a chance) they're being used to experiments. Rest in peace buds 🙁

  • I can never understand how people who are ok with abortion say that a fetus is not a living human being. This video shows that IT IS A HEART-BEATING HUMAN BEING!

  • Take a real close look at what the future holds for the next generation..
    Cloning people in a jar… Have you heard of Gays,, and Lesbian ‘s having their own kids yet or No kids at all ??
    Humanity will have to go on or face Extinction…. Think about the Big picture here ….And what’s written in the big book .. about Man laying down with Man and women laying down with women…

  • Your birthday is not the day you came out of the womb
    It's the day your mom discovered she's pregnant
    My real birthday is on may 15th, January 4th was fake all along!
    So my real birthday was weeks ago!
    (Just a random thought)

  • Tell me HOW all of this is a coincidence??
    There has to be a creator, a creator that wasn’t himself an embryo just like that.

  • Aww, so beautiful!!! Ii have a 17 year old and he is the best part of my life. It is beautiful to see, unless you aren't wanting a pregnancy. Leave the choice up to women, men. Especially in the case of rape, incest or if it could cause the woman to die if she goes thru with the pregnancy. To think our govt.would force a rape victim to go through with the baby conceived from rape is so frightening to me and I am post menopausal. It frightens me because at 18 I was gang raped and became pregnant. Back then it wasn't talked about as much as it is today, which still isn't enough. You can never get away from the scene of the crime because the crime is against the woman's body, let alone having to see your rapists face in your child, causing resentment and child abuse. (I realize men are raped, as well, but I am talking about pregnancy)Abortion was made legal for a reason. Too many women were needlessly dying because it was illegal. Abortions are safe when done in a safe environment by a Dr.or Dr.Assistant. But deadly when woman had to do it themselves with coat hangers. Men, do you really want your loved one to go through not only being forced to carry an unwanted rape baby to term, but after that, expect her (and yourself) to have a relationship with the rapist just because he is the so called father??? And you don't seem to care at all about them once they're born. Cutting education, healthcare, making our water & foods less safe….
    GOP- Get OuttaOur Panties!!

  • Lets not lie to the people and tell the truth. These evil people are doing all this to createa type of human they want modify, clone experiment on and who knows what else. They know how to do in vitro they know how to detect birth defects they have this masterd already. Think people before believing what u r told

  • On top of placing a human embryo inside a animal? For what? If this isnt perverse and twisted and abusive.

  • In New York, it’s legal to remove a baby out from the womb right up to birth! If that’s not Planned Parenthood, I don’t what is!

  • I take a test and it show that I am pregnant wasn't ready for it cause I have 2 and 1 is just 1 year and I used pill to avoid it don't know the pill didn't work.

  • Mind blowing yet we still have atheists in this world may Allah guide you not even saying it sarcastically ❤️❤️❤️

  • Can everyone stop complaining on how this is got in my recommendations YouTube places these vids on your recommendations based on the type of videos you watch

  • Wrong stop playing god let god mom and dads creat babies ok ans ussing them for other doings wrong too

  • I like how your calling it a baby because that's what it is, abortion is murder, and who gives a woman a right to play with life is she God

  • It's so ridiculous that on every scientific video, there's always tons of comments of people either pushing their faith on others or their ideologies. They just cannot keep their mindless comments to themselves. I guess no one cares for their opinions in real life, so they flood YouTube.

  • Well this is Ray before you even figure out your pregnant most of the time. No signal until the two week mark and a lot of people don’t catch it then.

  • i am 21 weeks pregnant and so excited to meet my baby
    tho i am only 23yo but marriage is so early in our tradition Lol
    i am not regretting it tho ..

  • This is incorrect according to pro choice feminists. Apparently there is nothing there other than a cluster of cells, just like a drop of blood is a cluster of cells

  • I was going to say this is unethical but being honest these are literally just cells. I’m pro choice 100% but at first even I thought this was unethical at first

  • I’m too young to have a baby I’m too young to have a baby I’m too young to have a baby I’m too young to have a baby


  • Wow, not only is it cells it’s a person. God told Jeremiah before he formed in the belly he knew Him! Science leaves that part out and the devil deceived women to think its their body and do what you want like Eve. Abortion is murder and it brings a curse on the woman’s body. Wake up. We have to be fruitful and multiply ..

  • You call it an embryo but whether you start it yourself or not, it is a baby that you are killing after 14 days. Are you so curious that your willing to kill off babies in the name of science. Just horrible! I love science but we have to ask ourselves, whats the cost of this research.

  • Look, a start of a new life, some call a bounce of cells without knowing they just insult a start of life

  • If you are dealing with an unwanted pregnancy, there are safe options.

    you can start looking at these options (the sooner the better) here:

    good luck!

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