Nigrostriatal projections in the rat as demonstrated by retrograde transport of horseradish peroxidase. II. Projection to the caudal striatum.

The distribution of nigral neurons projecting to the caudal and basal parts of the striatum was studied in 9 rats by means of the horseradish peroxidase labelling technique. Labelled neurons localized in the substantia nigra pars compacta were demonstrated throughout the antero-posterior extent of the nucleus. Most of them were found in the lateral half of the SNc. Labelled neurons localized in the substantia nigra part reticulata predominated in the caudolateral part of the SNr. Characteristic features included major perikaryal polymorphism and size range of the nigrostriatal neurons.