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Thread: Fetal Development

  1. #1 Fetal Development 
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    Hi Guys
    I was thinking over a baby's development in the mothers womb and a question popped up which I am not able to find an answer for. What are the stages of bone development in the fetus?


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  3. #2 Re: Fetal Development 
    Moderator Moderator TheBiologista's Avatar
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    Quote Originally Posted by Shaap
    Hi Guys
    I was thinking over a baby's development in the mothers womb and a question popped up which I am not able to find an answer for. What are the stages of bone development in the fetus?
    That just popped into your head?

    Homework?


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  4. #3  
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    Do they really teach that stuff in School these days...Hope you don't mind if I help out a little with a site or two, but I'd rather discuss it.....


    Shaap; This is a very good question, whether your a pending new mother, a student or just curious. I'll offer the following to help you, in any event. Out of my curiosity, just what did bring up this question in your mind? Oh yes, as an occasional occasional poster, WELCOME to the forum.

    Week 15: Baby's skeleton develops bone.
    Fifteen weeks into your pregnancy, or 13 weeks after conception, your baby is growing rapidly. Your baby's skeleton is developing bones, which will become visible on ultrasound images in a few weeks. Your baby's scalp hair pattern also is forming.
    http://www.mayoclinic.com/health/fet...opment/PR00113




    Bone Development and Structure
    Because bone is made up of minerals and is hard, many people think that it is not living material. But a bone in a living animal consists of both living tissue and non-living substances. Within the "alive bone" are blood vessels, nerves, collagen, and living cells including:
    http://www.nsbri.org/HumanPhysSpace/...velopment.html
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  5. #4  
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    Bone development is really interesting, because bone is not just a static organ - it is constantly being remodelled and reshaped throughout life by really active cells.

    First of all, the players:
    - Osteoblasts are bone forming cells
    - Osteoclasts are bone destroying cells - used to repair broken bones
    - Chondrocytes are cartilage producing cells

    Bone never develops directly, on its own. It is built upon cartilage - the hardish material of your outer ear and nose. So the first thing that happens is that chondrocytes, differentiated in the mesenchymal germ layer, form bands of Collagen Type I - a protein that forms tough rope-like fibers.

    Osteoblasts then surround the cartilage and 'mineralize it' with calcium. These calcium deposits are held in place by the Type I collagen in the cartilage and it forms a nice compact bone. In foetuses and adults, the bone grows from the centre outwards *axially* - so the bone lengthens over time. The tip of a growing bone is called the 'growth plate', this is where new collagen is made, and new mineral is deposited to lengthen the bone. Do you see how clever this is? When the bone grows long enough to meet its neighbouring bone, there is already cartilage present at the growth plate - and that cartilage is what forms the cartilage of your joints - nice and smooth to reduce friction and wear.

    Another clever thing about the way bone develops is that it is built to be strong in compression and in tension. For example, concrete is incredible in compression, but very weak in tension - it cracks if you pull it apart. Normally, a structure such as a cathedral is built for everything to be in compression (the genius of the arch). But to earthquake and wind-proof modern tall buildings, you need to build concrete to withstand tension by reinforcing it with steel girders that are strong in tension and weaker in compression. In this manner you get the best of both worlds: a material that is strong in tension and compression. By building bone (strong in compression) on top of collage Type I in cartilage (strong in tension), our body is really well engineered!

    An interesting, but tragic, disease exists called Osteogenesis Imperfecta (OI). In this disease, there is nothing wrong with the machinery for mineralizing the bone, but it is a disease in collagen type I. A mutation in the collagen prevents it from forming strong rope - it's like rope with a weak link in it - and a rope is only as strong as its weakest link. Since cartilage formation is needed for bone formation, the foetus develops little, and weak collagen. So its bones are small, and very brittle in tension. As adults, they are very very short, and very brittle individuals.

    Hope this feeds your interest
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  6. #5  
    Forum Cosmic Wizard spuriousmonkey's Avatar
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    Bone development is such a broad topic that you cannot give any meaningful general statement on fetal bone development. Especially since bone development differs in nature pending on spatial and temporal location.

    And then there are so many associated processes and topics with bone development.


    You could write easily a few hundred thousand pages on this topic and they did.
    "Kill them all and let God sort them out."

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  7. #6  
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    Thank you for the replies guys and no I am not doing this for homework, I am well beyond those years.

    Very interesting reads jackson33 and mascott. I have a more specific question:
    which comes first in the fetal development? The bone or the the tissue/flesh? If we take for example, when the arms and legs are forming, is the bone leading the way? so that as soon as some bone/cartilage has been formed then the required tissue/flesh develops around it. Or does the flesh/tissue develop first and then the bone through it? Or do the two happen interchangably?
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  8. #7  
    Forum Cosmic Wizard spuriousmonkey's Avatar
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    None of the scenarios you mention occurs. What does happen is specific for the location.

    So pick a location.
    "Kill them all and let God sort them out."

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  9. #8  
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    Ok, lets start with the arms and legs.
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  10. #9  
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    "Kill them all and let God sort them out."

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  11. #10  
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    Quote Originally Posted by Shaap
    which comes first in the fetal development? The bone or the tissue/flesh?
    The more complex parts grow larger, sooner. Like the spine, brain, digits. The simple parts catch up. A fetus has no butt because that's easily grown later.
    A pong by any other name is still a pong. -williampinn
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  12. #11  
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    Thank you for the replies guys.

    spuriousmonkey: The content on the link is too complicated for me to breakdown.

    Pong: Thanks for the additional info.

    I've been doing loads of research so I have a better idea of things now. Wikipedia states that the following happens between week 13-16:

    Quote Originally Posted by wikipedia
    More muscle tissue and bones have developed, and the bones become harder.
    Now my questions:

    1. In which week does the bone development begin?
    2. I presume that ligaments/tendons/muscle tissues develop over the bone, in other words, as the bone is developing the muscle tissues are developing over it. Am I Correct?
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  13. #12  
    Forum Cosmic Wizard spuriousmonkey's Avatar
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    Your question is too general to be answered meaningfully.

    I suggest studying the wikipedia article. It is extremely basic.


    Bones are very much dynamic tissues that are constantly remodelled. It's not a matter of getting more 'hard'. Bones can start off as cartilaginous tissues. Where the cartilage is slowly replaced with osteoblasts producing the bone matrix (and osteoclasts which get rid of it). Many bones grow only at a certain location which has then a special organization at this site.
    "Kill them all and let God sort them out."

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  14. #13  
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    spuriousmonkey, I am not looking for an detailed reply but something basic. The link provided is waaaay beyond my understanding. Now, according to wiki and a link posted earlier state that *more* bone develops at around week 15 (note Im not discussing its density/strength etc). Which indicates that bone formation has been taking place pre-15weeks. Certain groups of muscle are attached to the bone, so does that indicate the bone develops before the muscle?
    I mean we can say that most major organs have begun their development by around week 10, I'm sure there is alot more involved but one gets the general idea and can build upon that. Thats what Im trying to do with bone development.
    Thanks for putting up with me though!
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