Fig. 1.

Nigrostriatal dopaminergic pathway and neuropathological hallmarks of Parkinson's disease (PD). A. In the left hand-side, a sagittal schematic view of nigrostriatal dopaminergic (DAergic) neurons originating (in red) in the subtantia nigra pars compacta (SNpc) of the mesesencephalon, and projecting to the corpus striatum (CPu), which includes the caudate and putamen nuclei. The major neuropathological hallmarks of PD are boxed on the right-hand side. B. Schematic drawing of coronal brain sections at the level of the striatum and SNpc showing the trajectory (in red) of the nigrostriatal DAergic pathway. C-D: Confocal laser scanning microcoscopic images of Cpu and SNpc in coronal brain sections stained with the dopamine marker tyrosine hydroxylase (TH, in green) in intact, saline-treated mice (C) and after exposure to the PD neurotoxin, MPTP (D). Note the severe loss of TH⁺ fibers in Cpu and of TH⁺ cell bodies in SNpc, occurring in MPTP-induced PD (D). Scale bars, panel C (Striatum: 25 μm; SNpc: 100 μm), panel D (Striatum: 25 μm; SNpc: 100 μm).