Compartments in the striatum of the cat observed by retrograde cell labeling.

The distribution of neurons giving rise to striatal efferent projections has been studied in the cat by the aid of Mesulam's histochemical methods following large injections of horseradish peroxidase into the pallidum and substantia nigra. The findings suggest that neurons of medium size form a major fraction of the efferent neurons of the striatum and that these neurons are grouped into geometrically complex, three-dimensional networks.