We know, that cancer cell can travel across an organism.

Is this ABSOLUTELY impossible for NORMAL cells?

For example, is it EXACTLY ZERO probability to find some bone cells inside liver or some skin cells inside brain?

In non-living things and with molecules this is called "diffusion". Any two contacting things will penetrate inside each other after hundreds and thousands years.

Is something similar happening in living thing?

May be very slow?

Was this phenomenon searched for?

Are there some protection mechanisms against appearing wrong tissue cells inside another tissues?

I understand that cells appear in their places during grow, but in mature state I think it is not impossible for cells to travel.


I know that there are many cells that travel by nature, like blood cells.

The question is namely about "static" cells, those ones we normally regard as non-travelling.

Also, I understand that there are some mechanisms, making cells to prefer their normal places when they divide and grow.

But the question is what about all these mechanisms failed? And how often it happens?

For example, I am 40 y.o. So, how many bone cells from my legs are currently in my brains? Zero? One? Million?

  • $\begingroup$ hemotocyte (blood cell) travels quite a bit around the body. Lymphocyte cells go pretty. Lymphocyte (involved in immune system) can go in many different tissues. Does it answer your question? $\endgroup$
    – Remi.b
    Commented Jan 27, 2016 at 17:42
  • $\begingroup$ Depends on your definition of "normal," probably. There are non-cancerous diseases, like endometriosis, which involve cells ending up in the wrong place. $\endgroup$
    – AJK
    Commented Dec 20, 2017 at 6:37
  • $\begingroup$ Also, this is a potentially very difficult question because cell "type" is not as well-defined as you would like it to be. It is difficult to tell if a cell is in the wrong place ("ectopic") or just a strange variant of a normal cell type. $\endgroup$
    – AJK
    Commented Dec 20, 2017 at 6:42

1 Answer 1


In a healthy body, cells travel. But this is very dependent of the cell type. Some cell type will travel in all the body (lymphocytes, plasmocytes, etc) while other do not have any migration capability.

The concept of diffusion is wrong to apply here, indeed the scales at which you are looking are not molecular.

Moreover, there are very active mechanism to keep cell type in place, for example, a concept called preferential attachment will maintain the cells grouped by cell type. If you take two balls A and B and A attached more to A and B to B, and you shake, you will see appearance of clusters of A and clusters of B. But that is only one such mechanism and a lot of other take play here.

see this: http://www.ncbi.nlm.nih.gov/books/NBK26937/

Thus, the probability of finding a cell type NOT at its normal position (that is one that does not travel) is maybe not zero, but so close to it that you will not find a cell outside of their normal position.

I hope this answers your question ?

Cooper GM. The Cell: A Molecular Approach. 2nd ed. Sunderland (MA): Sinauer Associates; 2000

  • 1
    $\begingroup$ Looking at it on my desk, I can't really find a chapter on this, it is too broad a question, it encompasses things from caderine adhesion, to Blood brain barrier. The most relevant thing I found to this question is probably this: ncbi.nlm.nih.gov/books/NBK26937 $\endgroup$
    – Xqua
    Commented Jan 28, 2016 at 22:56
  • $\begingroup$ Agreed on that. It's very broad. Good attempt though. +1d already :) $\endgroup$
    – AliceD
    Commented Jan 28, 2016 at 23:44
  • $\begingroup$ The preferential attachment mechanism can't be 100% accurate as anything in nature. Even the very term "preferential" implies uncertainty, because it would called "exclusive attachment" otherwise. $\endgroup$
    – Dims
    Commented Feb 8, 2016 at 14:31
  • $\begingroup$ So, the question is namely about cell types we normally regard as non-travelling. For example, can we find bone cell in brain or skin cell in eye? I agree that probability is not zero, but the question is how large is this probability? $\endgroup$
    – Dims
    Commented Feb 8, 2016 at 14:33
  • $\begingroup$ The concept of diffusion is actually very relevant - it's one aspect of how you would model the motion of a single cell! $\endgroup$
    – AJK
    Commented Dec 20, 2017 at 6:38

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