Distribution of the nigropallidal neurons in the rat. (An experimental study using HRP and iron-dextran).

The distribution of nigral neurons retrogradely labelled from the globus pallidus was studied in 9 rats using the horseradish peroxidase and the iron-dextran labelling technique. Retrogradely labelled neurons significantly prevailed in the ipsilateral substantia nigra pars compacta. Labelled neurons localized in the ipsilateral substantia nigra pars compacta were demonstrated throughout the anteroposterior extent of the nucleus and prevailed in its lateral half. A small number of labelled neurons was found in the lateral part of the ipsilateral substantia nigra pars reticulata, in the ipsilateral ventral tegmental area and in the contralateral substantia nigra pars compacta. A considerable perikaryal polymorphism and differences in the size are characteristic of the nigral neurons labelled from the globus pallidus.