Fig. 6.

Temporal evolution of tα-syn presence in the brain after injection in the OB. a Drawings representing schematic horizontal sections of the brain with the different regions exhibiting huα-syn-positive cells or a diffuse BSA-staining at different time points after protein injection in the OB. b BSA and huα-syn staining 12 h after injection in the OB. We detected huα-syn-positive cells in the ipsilateral OB, and FC after injection of monomeric, oligomeric and fibrillar tα-syn, as well as in the ipsilateral AON after injection of oligomers. On the contrary, we did not find BSA-positive cells in the brain 12 h after tBSA injection in the OB. Huα-syn-positive cells appeared to be either mitral/tufted cells, located in the external plexiform (EPL) and mitral cell (Mit) layers of the OB (in groups injected with oligomers or fibrils, grey arrows), or displayed the morphology of microglial cells (in groups injected with monomers, oligomers or fibrils; black arrows). Scale bar represent 25 μm. c Huα-syn- and BSA-staining 72 h after injection in the OB. Huα-syn-positive cells were detected in the ipsilateral OB, AON and FC after injection of monomers, oligomers and fibrils 72 h after injection, and those cells exhibit a microglia-like morphology. On the contrary, no BSA-positive cell was found in the brain 72 h after tBSA injection in the OB. Scale bar represents 25 μm