For double tracing experiments, wheat germ agglutinin (WGA) molecules labeled with two different haptens are desirable. In the present report the suitability of digoxigenylated WGA (DIG-WGA) for retrograde tracing was investigated. For this purpose the new tracer was pressure injected into rat brains and the transported DIG-WGA visualized via its digoxigenyl group with an alkaline phosphatase linked anti DIG antibody in permanently stained sections of high quality. With fixatives containing 2.5% glutaraldehyde only few positive cells were found. However, at milder fixation conditions (4% paraformaldehyde, 0.05% glutaraldehyde 0.2% picric acid, 30 min) retrogradely labeled cells were detected with a sensitivity comparable to tetramethylbenzidine protocols for conventional WGA-HRP (horseradish peroxidase) tracing. Preliminary experiments suggest excellent suitability for double labeling.
Alkaline Phosphatase Animals