NTR: myelinating glial cell

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Doug suggests this NTR. See:

https://sourceforge.net/p/geneontology/ontology-requests/11392/

We have

 * CL:0000328 ! myelin accumulating cell (undefined in CL, inherited from initial version of CL).

This includes 'myelinating Schwann cell', but not oligodendrocyte.

Anyway, I think this class is weird, and should be obsoleted with a consider to 
CL:new 'myelinating glial cells'

CL also makes a distinction between plain Schwann cell and 'myelinating Schwann 
cell'. Do we need the latter?

{{{

         is_a CL:0002573 ! Schwann cell [DEF: "A glial cell that ensheathes axons of neuron in the peripheral nervous system and are necessary for their maintainance and function."]
          is_a CL:0000218 ! myelinating Schwann cell ***  [DEF: "A neuroglial cell of the peripheral nervous system which forms the insulating myelin sheaths of peripheral axons."]

}}}

By the text defs, these should be merged. Are there unmyelinating Schwann cells?

A complicating factor is that 'myelin' is found in non-vertebrates but these 
may be functional analogs, and the method of producing 'myelin' may be 
different. See: PMID:19508741

Original issue reported on code.google.com by cmung...@gmail.com on 9 Dec 2014 at 10:47

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Both myelinating and non myelinating Schwann cells do exist.

Original comment by doug.g.h...@gmail.com on 9 Dec 2014 at 11:05

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Doug, agreed, my point was that the text defs are almost identical and by that 
criterion should be merged.

The differentia is buried (that the sheath is made of myelin). This needs to be 
brought to the fore.

How should we make the equivalence axioms?

 myelinating Schwann cell = Schwann cell and has_part some GO'myelin sheath'
 non-myelinating Schwann cell = Schwann cell and has_part some GO'???'

What's a good ref for the non-myelinating form? Current def uses generic source.

Original comment by cmung...@gmail.com on 10 Dec 2014 at 10:03