Fig 1: (a) Immunofluorescence image of a sagittal section from a human PD OFB stained with antibodies for PGP9.5, CNPase, NeuN, UEA-1, and a Hoechst counterstain to identify the AON regions. Phosphorylated a-syn (s129) antibody was used for the distribution of a-syn. (b) Illustration of the PD OFB and tract displaying the distribution of a-syn, highlighting that most of the a-syn inclusions are in the multiple AON regions. (c) Inset of AON 1 showing representative immunofluorescence images used to identify the AON region. The AON is characterized by a decreased density of cells represented with Hoechst staining, increased PGP9.5 immunoreactivity, a lack of CNPase immunoreactivity and increased density of large NeuN-positive cells. In PD OFBs, the increased abundance of a-syn can be used to identify the AON. Scale bar, 1 mm (a) and 500 µm (c). Graphs showing (d) area fraction of a-syn (%) inside versus outside of the AON of human PD OFBs (n = 11) and (e) area fraction of a-syn (%) inside versus outside of the AON by case. Data presented as mean ± SD. # p < 0.0001, * p < 0.05.