Long distance tracing with biotin?

[Philip Collman]

I want to do some experiments tracing from the CNS to the gut, with the
aim of labelling vagal afferent and efferent terminals in the periphery.

I am aware of the studies using DiI, but I need something which will give
a better EM label. I was thinking of using biotin, biocytin or
biotin-dextran-amine, but I can't seem to find any references to anyone
having used these compounds to trace over long distances i.e. outside the
CNS.

Does anyone out there have any relevant experience?

Thanks!