Fig. 4

Macroscopic distribution of iron in the substantia nigra obtained by Perls ‘ staining and R2* mapping (MRI). In controls (Co), the area near nigrosome 1 can be delineated by a comma-like hypodense signal (arrows) in both Perls’ staining (A) and MRI R2* maps (C), surrounded by two tails of hyperdense signal, giving rise to the typical “swallow tail” structure. This “swallow tail” pattern disappeared in PD (B, C) because the iron is distributed rather homogeneously, where iron distribution obtained by Perls’ staining (B) shows a more homogeneous distribution throughout the SN. Scale bar 1000 µm