The histochemical reaction of horseradish peroxidase in rodent 'whole-brain' preparations.

Subsequent to eye injections of horseradish peroxidase (HRP) 'whole-brain' preparations with only the cortex removed were reacted for HRP using tetramethylbenzidine (TMB) as the chromogen and ammonium heptamolybdate (AHM) as a stabilizer. Retinal projections could be photographed and visualized globally coursing across the surface of the thalamus and midbrain. The brains were then sectioned, and when necessary re-reacted, enabling a 3-D reconstruction of retinofugal pathways to be made.