DIFFERENTIAL LABELING OF CONVERGING AFFERENT PATHWAYS USING BIOTINYLATED DEXTRAN-AMINE AND CHOLERA-TOXIN SUBUNIT-B

We report a new technique for 2-tracer anterograde labeling that permi ts unequivocal identification of the differentially labeled projection s in the same section. One pathway is labeled with biotinylated dextra n amine and is visualized as a black to dark gray diaminobenzidine (DA B)-cobalt precipitate by an avidin-biotinylated peroxidase reaction. T he other pathway is labeled with cholera toxin subunit B and is visual ized as a reddish-brown reaction product using DAB without cobalt as t he substrate for peroxidase immunohistochemistry. To maintain serial o rder, sections can be processed mounted on slides without any loss of sensitivity for either tracer.