Photos of chicken forming in egg


Here's one photo of a series of about 20 photos showing a chicken developing in an egg. Before I saw these photos I had always thought that the yolk turned into a chicken, but it looks like the chicken forms outside of the yolk and absorbs the yolk as it develops. Link


  1. I was always convinced that the part that turned into the fetal chicken was that little white vein junk that floats around connected to the yolk. I can’t tell if I’m right or not. But interesting anyway.

  2. Yeah it’s the little white thing that would have been the chicken had it not been murdered in the womb…

  3. #3 – That’s what I’d thought to. In fact, I usually scoop that out when making eggs and throw it away rather than eat it because it somewhat disgusts me to eat it. Though I eat chicken. And eggs. Hmm.

  4. @4: you need not worry. The eggs you buy in the supermarket are unfertilized, so no murdering has taken place. Menstruation, yes.

  5. Actually, the little white strings are suspensory structures called chalazae that hold the yolk in the middle of the albumen. The thing that becomes a chick will be a little white dot on the surface of the yolk called the germinal disc. Of course, unless you’ve specifically bought fertilized eggs, there’s nothing in a chicken egg that will become a chicken. So it’s not really murder, more like a chicken “period.”

  6. There is an important distinction between unfertilized eggs and murdered fertilized eggs. The unfertilized egg (which is what is sold in stores, but is hard to verify in case one of the chickens somehow met a rooster along the way) has no murdered chicken inside of it because it never was able to start growing without the male’s fertilization.

    There is a little part on the fertilized yolk that is the origin of the chicken (called the germinal disk). The germinal disk is not visible if the egg has not been fertilized. As the It is not the white vein junk, that stuff is called Chalaza and acts as suspension for the yolk in the egg.

    The yolk is pure nutrition for the developing chick, think of it like the placenta (not sure if that helps make it less disgusting, but it is just a sack of nutrients).

  7. That’s not the birth of anything. All those chickens were killed, albeit at instructive times in their development.

    Seeing that last one alive was a bit disconcerting.

  8. lol @ 4

    An egg that you eat (supermarket egg) is just a Chicken’s Period, excpet instead of absorbing it with a bit of cotton like human periods, you’re eating it.

  9. Unless I’m gravely mistaken, my fourth grade teacher did a science unit like this with our class. We had an incubator and a lot of eggs in our room. Everyday, she would break open another egg so we could see how the chicks were developing, and I think we each drew a picture in our science journals. The funny thing is that I don’t remember being upset by the idea that the revealed chicks were being killed as a result; I don’t even remember being aware of that thought. We were just terribly excited about the day when the chicks would finally hatch!

  10. I was always aware that the yolk was a food source to a potential chick (a benefit of country livin’). I’m honestly surprised how much the idea that the yolk (that you EAT!) turning into a living chicken repulses me.

    The eggs that you buy from the supermarket are unfertilised and can never have a chick inside. It’s not just a lucky coincidence that you’ve never cracked an egg and found a chick – the chickens that laid it are not exposed to any males.

  11. Repeat after me:

    Menstruation has nothing to do with eggs. Ovulation produces eggs. Menstruation is the shedding of the uterine lining, the endometrium. Menstruation occurs only in some mammals. Chickens are not mammals. I will not sleep through high school biology again. I will not sleep through high school biology again. I will not sleep through high school biology again.

  12. I thought that was interesting! I also figured the yolk is what becomes the chicken, but I guess it makes more sense that it would be a source of nutrients for the fetus.

    We never got to see stuff like that in school. All we ever did was dissect owl pellets, earthworms and frogs.

  13. The best part was the link at the top of the article, that had a Moth’s life in pictures.

  14. Pandas freak me out. They’re like some horrible, stuffed-animal-come-to-life nightmare.

  15. There is no context or other information. Is this a series of different eggs, as seems inevitable, or some miraculous process whereby a chicken embryo could be hatched sans eggshell? Some metadata would be most welcome.

    Because if it is just a series of pictures of cracked shells, the live chick at the end is a cruel joke.

  16. To be fair, they saved the chicks from a fate worse than death (have you seen a docu on their lives from conception to tasty snack?)

  17. Could any of you eggsperts tell me why I always find a purplish/red spot in my unfertilized eggs? I spend ages getting the slippery bugger out, using a couple of teaspoons. Offends my vegetarian sensibilities as it looks a bit bloody…

    Cool pictures – especially the veins bedding in like roots.

  18. Flu vaccines are prepared in fertilized chicken eggs (about 100 million per year to supply the US). The influenza virus is injected into eggs, and some time later, the infected embryos are harvested. (The technical term for “getting pureed”, I assume. I’m all for vaccination, but talk about offended vegetarian sensibilities…) I haven’t found much in a quick web search, what would the corresponding development stage be here?

    @jakea: Sounds like “blood spots”, hemorrhages of a small blood vessel when the egg is formed.

  19. Norm&Al

    You know, I wondered what would prevent an egg with the shell removed from developing properly. Apart from the extreme dexterousness of getting the shell off wilst leaving the inners intact, and maybe the possibility of the chick bursting it’s membrane accidently..
    in any case, you could probably do the shell-getting-off with a bit of practice, and maybe cover the unshelled membrane with some sort of clear, protective coating..


    Vegetarians eating eggs always seemed pretty funny to me. Especially when they eat fish too. (not that I’m disparaging, just observing)

  20. IIRC, last time I was at the Exploritorium in SF, they had an exhibit with live chicken embryos demonstrating the same thing.

    I’m actually a little surprised the Exploritorium doesn’t get more love here — it’s all about hands on, DIY scientific exploration.

  21. Everyone one of these photos (except the last) involved breaking a developing egg and killing the fetus.

    Gandalf: “He that breaks a thing to find out what it is has left the path of wisdom”

  22. @arkizzle: Approximately 80% of the calcium for the chick skeleton comes from reabsorption of the egg shell.

  23. @argon: thanks, so technically I’m right to pick them out. Chicken’s blood in my otherwise pure egg.

    @arkizzle: i do find eggs hard to stomach sometimes, but the chicken doesn’t have to die for you to eat an egg (unlike fish, where it’s curtains for the fish), so like milk eggs are more acceptable to me. But given that I stopped eating meat because of squeamishness, imagining the exact constituents and origins of an egg can have me pushing it around the plate. That’s why I always go for scrambled, not fried. You can forget it’s an egg.

    Question is, can caviar be harvested without killing the fish, and if so, does that make it vegetarian?

  24. @ #35: But that can’t be a particularly big percentage of the shell, right? I mean, the little chicks still break out of a shell that’s not noticeably thinner than it was before.

    If you were to carefully remove half the shell in such a way that the inner layers remained intact (and then replace that half with some transparent protective covering), I bet that the chick could still get enough calcium from the other half of the shell.

  25. @ #36: Caviar is always harvested without killing any fish — it’s not “curtains” for anyone.

    Caviar is made out of roe, which is unfertilized fish eggs. In nature, the roe would normally be deposited somewhere and then sprayed with male fish sperm, fertilizing them. For caviar, the roe gets harvested after it is naturally laid.

  26. jakea, does that mean you would eat Takuan’s cow-ass-lobes if they didn’t kill the cow? (No, it didn’t sound appetizing to me either, and I love meat) :)

  27. SamSam, re:#35

    Yeh, that was my first thought too, there is a whole lot of egg at the end of the process, so we could just remove that amount in the first place and whatever bit we leave can be the calcium supply.

  28. I might be too late to this chicken party for anyone to read this, but just in case Google ever sends someone to this post, some more info:
    It is NOT true that all supermarket eggs are un-fertilized. A hen does not start producing eggs until she’s mated with a rooster at least once. Science and farmers disagree over whether or not hens need continued mating to remain productive.
    Part of the egg-grading process includes candling – each egg is held up to to a lamp where an experience egg-grade can determine whether or not the egg was fertilized. If fertilized, it’s discarded.
    (Actually, I should correct myself here.. many many many eggs are now produced by never-mated hens. That’s because they are fed / injected with hormones to induce ovulation extra-naturally. I don’t recommend eating this eggs. At the very least, they don’t taste as good. At worst, feeding them to your daughters might cause them to start ovulating before they’re 9 years old)
    However, just like all quality control mechanisms, it’s not perfect. If you eat a LOT of eggs, you will eventually run across one that has what’s called a “blood spot.” That’s basically a chicken zygote.

    As an interesting aside, eggs with blood spots in them violate the Jewish laws of kashrut. Unfertilized eggs are considered pareve (neither meat nor dairy), but a fertilized egg is verboten (though removing a blood spot from a dozen cracked eggs makes them acceptable… whereas removing a speck of bacon from otherwise kosher food does not make it acceptable).

  29. @#31 – I work in a research lab that uses developing chicken embryos – there’s a certain cluster of neurons that’s a really good place to study how neurotransmitter receptors get to the developing synapses. We don’t do vaccine production, but we do cut a window in the shells at an early stage to inject a virus that manipulates the receptors. You can infect different parts of the embryo depending on the stage – the first, second, and 3rd pictures look like the stages we use. After injecting, we put a piece of packing tape over the window and keep them in an incubator until they’re developed enough to use. (Our animal-use protocols don’t let us hatch them.) Not all of them survive, but that’s more because of the stress of the injection than the loss of the small circle of the shell.

    It’s really interesting to see something like this posted in a more public forum! I hope I haven’t offended anyone who’s against the use of animals in research by posting details; if I did, I absolutely apologize.

  30. #42 ellkaiesse5
    I’m sure it’s fine. Check out a similar discussion over on the Bionic Monkeys thread. You could probably provide some useful input to the discussion.

  31. @ #38:

    Typically, the fish ARE killed to obtain the roe. It is most certainly not harvested by divers as it lays peacefully on the ocean floor.

    Slate says, “Almost all caviar is harvested from dead fish. Fishermen on the Caspian wait until the mature female sturgeon (which are at least 10 years old) are ready to migrate upstream and lay their eggs. Once caught, the sturgeon will be transferred to a large boat, where workers slit her open and remove her eggs.”

  32. @arkizzle: Ah I see, by “an egg with the shell removed” you didn’t mean all of it, as in, removing the shell and squeezing the remainder into a test tube to look at it. I’ve no idea how much of the shell must remain for proper development.

    @drewstarr: see link in post #31, an egg with a spot doesn’t necessarily mean it’s fertilized

    @ellkaiesse5: I’d never do animal research myself, but I won’t blame the rest of the world for not following my own ethics, at least in this case. Glad to hear you limit it to the earlier stages though. Yes, I’d be freaked out if I’d be working on something that was developing eyes. :) Not offended at all, for my part. More importantly – if one wants to get a fair debate from everyone, even at the risk of alienating some people, the last thing one should do is to be ashamed of providing details.

  33. Argon:
    No, i actually did mean remove the whole shell, but more like keeping the membrane intact and holding it in suspension or some safe construct, than “squeezing the remainder into a test tube”.

    I didn’t know about the calcium benefits of the shell though, so I amended the suggestion. But I do wonder what percentage of the shell goes toward the chicken’s calcium needs, and therefore, how much surface area you could remove without disturbing it’s development.

  34. @33merreborn

    I’m actually a little surprised the Exploritorium doesn’t get more love here — it’s all about hands on, DIY scientific exploration.

    Get a camera, a blog, and send us the URL! Sounds like a great place, I’m sure they’d feature some of your posts on BB.

  35. #36 and #38. Wishful thinking: “Caviar is made out of roe, which is unfertilized fish eggs. In nature, the roe would normally be deposited somewhere and then sprayed with male fish sperm, fertilizing them. For caviar, the roe gets harvested after it is naturally laid.”

    Nope… slit the bellies of females ready to lay the eggs… that’s how it’s done. Not that I don’t eat fish, but let’s not fool ourselves.

    The chicken embryo pix are fascinating, though. I was always the one who couldn’t wait to do the dissections in 10th grade biology, though.

  36. Yeah, the Exploratorium is awesome… haven’t been there in years, but in my early teens it was a must-see every time I visited my relatives in San Francisco.

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