Fig. 5

Severed axons regenerate faster in SIRPα−/− mice than in wild-type mice. Axons and macrophages were visualized in intact and Wallerian degenerating (a) saphenous and (b) sciatic nerves by immunofluorescence microscopy using Abs against neurofilaments (NF; red) for labeling axons and mAbs against the αM/CD11b subunit of CR3 (green) for labeling macrophages. The overlay of NF/red over CR3/green is yellow. Hoechst staining visualized nuclei (blue). a Intact (0d) and freeze-crushed saphenous nerves were sampled at distances ranging from 8 to 10 mm distal to lesion sites 2, 4, and 7 days (2d, 4d, and 7d) after surgery. b Intact (0d) and freeze-crushed sciatic nerves were sampled at distances ranging from 8 to 10 mm distal to lesion sites 3, 7, and 9 days (3d, 7d, and 9d) after surgery. Initially, on days 2 and 3 after surgery, NF immunoreactivity decreased in wild-type (WT) and SIRPα−/− mice. Then, at the indicated days thereafter, NF immunoreactivity increased more in SIRPα−/− mice than in wild-type mice. CR3 immunoreactivity that was hardly detected in intact nerves (0d) increased as of days 2 and day 3 after surgery onwards in saphenous and sciatic nerves of both WT and SIRPα−/− mice; arrows mark some of the CR3 expressing cells. Shown are representative images from four nerves that were sampled at each time point. Bars: 20 μm in a and 100 μm in b