Fig. 3

Arginase 1 expression is primarily associated with macrophages within crush sites. A. Diagram showing WT animals given a unilateral 7 d crush CL, followed by crush TLs with a 2 d or 5 d regeneration period. The dotted box indicates the area examined in the assays. The “Sham” contralateral nerve only received the TL. B-C. Representative sciatic nerves from animals given a crush CL and a 2 d TL, immunostained for the macrophage marker CD68 and the proregenerative macrophage marker arginase 1 (Arg1). D-E. Representative sciatic nerves from animals given a crush CL and a 5 d TL, immunostained for CD68 and Arg1. For B-E, the dotted line indicates the center of the crush TL which was nominally 600 μm wide, and the box is 600 μm wide and placed at the crush CL. F. Macrophages at and immediately distal to the TL site represented by CD68 percent area stained. CD68 was measured for all groups by placing a 600 μm wide rectangular ROI centered over the TL site (Lesion Site) and then a second 600 μm wide ROI adjacent to the distal edge of the first ROI (Distal Nerve). ROIs were adjusted for the height of the nerve. G. M2 phenotype in macrophages at and immediately distal to the TL site represented by Arg1 percent area stained. Arg1 was measured for all groups as in F. H. Macrophages at and immediately distal to the CL site represented by CD68 percent area stained. CD68 was measured for all groups as in F except the first ROI was placed over the CL site. I. M2 phenotype in macrophages at and immediately distal to the CL site represented by Arg1 percent area stained. Arg1 was measured for all groups as in H. Scale bar = 500 μm. * p < 0.05; ** p < 0.01; *** p < 0.001. N = 4–5 per group