Figure 2.

A–C. Photomicrographs of tissue dual immunostained for p75^NTR (brown) and pS422 (dark blue/black) in the anterior subfields of the nbM showing the presence p75^NTR containing pS422 inclusions (dark blue) and neuropil threads (dark blue) in CTE stages II (A), III (B) and IV (C). Note that many more double p75^NTR/pS422 positive neurons and neuropil threads (dark blue) were seen in stage III and IV compared to stage II. D–G. High power images of double immunolabeled p75^NTR/pS422 neurons in the anteromedial nbM showing intraneuronal cytoplasmic pS422 imunoreactivity (black) containing granular (D and E), filamentous (F) and skein of yarn-like (G) phenotypes in a stage IV CTE case. H and I. Twisted filamentous p75^NTR positive inclusion (blue) resembling a skein of yarn in the nbM neuropil. Arrows indicates a double immunolabeled p75^NTR/pS422 neuron in I. J–L. Photomicrographs of single TOC1 (brown) (J and L) and dual immunolabeled p75^NTR/TOC1 (dark blue/black) neurons and neuropil threads in anterior subfields of the nbM in a stage II (J), III (K) and IV (L) CTE cases. Note the increase in the extent of TOC positive neuropil threads in stage IV. M and N. Insets showing higher magnification images of granular (small arrow), compact spherical (M) and twisted-filamentous (N) TOC1 immunoreactive profiles (brown) in the anterormedial subfield of the nbM neurons from panel L (arrows). O–Q. Photomicrographs of double immunolabeled TNT1/p75^NTR (dark blue) (O) and single reactive TNT1 (brown) (P and Q) positive neurons and neuropil threads in the anterior subfields of the nbM from a stage II (O), III (P) and IV (Q) CTE cases. R and S. Insets showing details of the granular and filamentous TOC1 immunoreactivity in anteromedial subfield of the nbM neurons from a stage IV CTE case. Tissue was counterstained with cresyl violet in panel P. Scale bars: 75 µm (A–C), 65 µm (L, O, Q), 50 µm (K, P), 25 µm (J), 15 µm (M, R, S), 12 µm (G), 10 µm (D, E, H) and 8 µm (F, I, N).