#11769 axon vs. nerve fiber

[Michael E Rice]

I would like to have a term for "nerve fiber" but I am having difficulty finding agreement on the difference between axons and nerve fibers. From Uberon we have the Wiki definition:
nerve fiber(UBERON:0006134)
A threadlike extension of a nerve cell and consists of an axon and myelin sheath (if it is myelinated) in the nervous system.

but this reference sounds like an axon is a myelinated nerve fiber, cf. p13 The Axon: Structure, Function, and Pathophysiology Stephen G. Waxman, Jeffery D. Kocsis
Oxford University Press, 1995

see also
PMID: 16589576

Afferent fibers are dendrites, and efferent fibers are axons, but any peripheral nerve fiber of unspecified nature is commonly called an axon
http://www.bio.fsu.edu/easton/topic13.html

Therefore we could have a GO:ID for:
nerve fiber
is_a GO:0030424 axon
part_of GO:0043209 myelin sheath

or include in the definition for GO:0030424 axon indicating that when myelinated it is called a nerve fiber or the other way around? Maybe you can have better luck nailing down the definitions but please do not spend an excessive amount of time with it.

Thanks

[David Hill]

Since the axon and the myelin sheath are parts of two different cells and would be collectively referred to as the nerve fiber in myelinated axons, then it is really an anatomical structure and not a cellular component. It is correct for it to be in UBERON. A nerve fiber would always have an axon as a part, since this would cover both myelinated and non-myelinated axons.

Would it be ok to make 'nerve fiber' a related synonym of axon?

I suspect if we are to make an annotation to a cellular component, then we should have the specificity of the axon or myelin sheath. If we know that the axon is unmyelinated, then we know that axon is the correct cellular component. If the axon is myelinated and the specificity is not known, then the anatomical structure is the best we can do.

-D

[Michael E Rice]

[David Osumi-Sutherland]

I think 'nerve fiber' would be better as a synonym for the more general term 'neuron projection' (AKA neurite). That way it covers both axons, dendrites and unclassified neurites. I'm not sure we need a term for axon + myelin sheath. Hard to support, and, for the reasons DH outlines, cannot be a GO term (although Uberon might support it).

[Michael E Rice]

[David Hill]

Done.