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Thread: Just Being Nosey

  1. #1

    Just Being Nosey

    Wise

    It seems to be my position in life to ask you annoying questions so here's another one

    What is the difference (if any) between axons in the nose and axons in the spinal cord?

    As you've told us, transplanting oeg into the spinal cord seems to allow only slight regeneration and other treatments will need to be combined with oeg to get a significant amount of regrowth.

    Why do the axons in the nose manage to regenerate presumably without these other elements. Are they different from other cns nerve fibres? Is it the sheer quantity of axons required in the cns that is the difference?

    Thanks!

  2. #2
    Chris2,

    Perhaps the following information will help you answer the question. I am not sure that I have the answer.

    1. The olfactory nerve is a short nerve. The lamina propria of the nasal mucosa is located at the base of the skull and the olfactory nerve enters the skull cavity through perforated bony areas called the cribiform plates. The olfactory bulb is situated just above the cribiform plates. So, the regeneration distance is very short, probably no more than 5 mm. In contrast, the spinal cord is over 500 mm (half of a meter) long and regeneration distances are much greater.

    2. Regeneration is occurring continuously in the olfactory system but axonal growth may have been stopped for weeks in rats or years in people with chronic spinal cord injury. There is a need to "kickstart" the growth.

    3. Regenerating spinal axons have to traverse not only an injury site that may be several centimeters long but they must grow all the way back to their original targets that may be hundreds of millimeters away.

    4. Long-term followup data is not yet available for OEG transplants.

    Given this situation, I suggest that we reserve judgment on what OEG can do alone and in conjunction with other therapies until more data is available.

    Wise.

  3. #3
    yes I see

    there is a lot of difference

  4. #4
    Chris2, I do want to point out that olfactory nerve regeneration may be limited in some circumstances. For example, many people who have had traumatic head injury lose their sense of smell. The reason is that the olfactory nerve is sheared by the sudden deceleration. When the olfactory nerve has been sheared in this way, scar tissue forms in the holes of the cribiform plate and the olfactory axons cannot grow back. Many people with head injury lose their sense of smell and it takes a long time or does not come back. Wise.

  5. #5
    yes and the axons in a spinal cord injury have to cross an injury site and cannot do it - normally in the nose there is no injury to cross.

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