SITS: a covalently bound fluorescent retrograde tracer that does not appear to be taken up by fibers-of-passage

Abstract

Experiments in the rat indicate that the plasma membrane marker SITS is a sensitive retrograde tracer that is not taken up in detectable amounts by preterminal axons. SITS contains a reactive isothiocyanate group that binds covalently to proteins under mild aqueous conditions, and its use is fully compatible with autoradiographic, HRP, and immunohistochemical methods, as well as with certain other fluorescent tracers. In addition, it neither diffuses from retrogradely labeled cells, nor is degraded after prolonged survival times.