Enhancing the anterograde movement of HRP to label sparse neuronal projections.

By combining techniques designed to increase the amount of horseradish peroxidase (HRP) available for transport and to improve the sensitivity of the reaction for detecting HRP, we have produced an anterograde HRP technique suitable for labeling sparse efferent projections. The efficacy of this light, microscopic technique was demonstrated by lebeling the hippocampal commissural and crossed temporo-ammonic projections to the dentate gyrus of the rat.