Calretinin as a marker of specific neuronal subsets in primate substantia nigra and subthalamic nucleus

Neurons immunoreactive for the calcium-binding protein calretinin (CR) were visualized in the substantia nigra (SN) pars compacta (SNc), reticulata (SNr) and lateralis (SNI), the ventral tegmental area (VTA) and the subthalamic nucleus (STN) of squirrel monkeys. The density of CR perikarya was high in VTA, moderate in SNc, low in SNr/SNI, and very low in STN. The SNc/VTA complex also displayed a CR-rich neuropil. Some CR perikarya and fibers occurred in specific sectors of STN. These data suggest that CR may play a role in specific neuronal subpopulations in all components of primate basal ganglia.