Fig. 4.

Histological analysis of the peroneal nerve. A Number of axons at the proximal, medial (vein bridge) and distal parts in the four groups of rats. Above, Neurofilament (NF-L 70) immunohistochemistry stains in each group. Involved in the maintenance of neuronal caliber, neurofilaments are the intermediate filament proteins found specifically in neurons, and are the structural components of axonal processes. Scale bar, 200 μm). The number increased in both the VE-fEV and VE-cEV groups, in the medial and proximal parts, when compared with VE group. When compared with GS, the number of axons only increased in the medial part for the fEV-treated animals. B Quantitative analysis of the G-ratio in the three groups observed. Above, representative TEM images of peroneal nerve in each group. Scale bar, 15 μm. No significant difference was observed between VE, VE-fEV and VE-cEV groups, even if the G-ratio decrease towards Control value (dotted line) for both fEV and cEV groups, in proximal, medial and distal parts of the damaged nerve. 1 symbol: p < 0.05; 2 symbols: p < 0.01; 3 symbols: p < 0.001. Dotted line, mean value of Control; GS, Gold Standard; VE, Vein; VE-cEV, Vein-cryoconserved extracellular vesicles; VE-fEV, Vein-freshly purified extracellular vesicles