PiT1 immunostaining in normal and MPTP-intoxicated mice. A: PiT1 staining in the cortex of control mice; stained neurons are mostly detected in layer II/III. These neurons are medium-sized with homogeneous cytoplasmic staining. B: PiT1 immunostaining in the corpus callosum (CC) of normal mice: PiT1 labelling exhibits a linear pattern with few stained cells following the myelinated fiber bundles corresponding to oligodendrocytes (arrows). C: PiT1 immunostaining in the SN of normal mice with a reticular pattern due to a relative sparing of white-matter (arrows). D: PiT1 immunolabelling in MPTP intoxicated mice where an apparent extension of staining can be seen in the white-matter bundles in the substantia nigra pars reticulata (SNpr) and in the cerebral peduncle (CP). The staining is presented as follows: A to D, staining with Alexa 488 (green, PiT1 ligand) and A and B, signals are merged with Hoechst (blue, counterstaining for nuclei). Scale bar: 100 μm.