Effect of aging on the recruitment of CXCR4+ cells to burn wounds. Tissue was harvested from young and old 129S1/SvImJ mice on day 3 after burn wounding and sections were analyzed by immunohistochemistry using anti-CXCR4 antibody. a, b Representative sections of wound and adjacent areas (BW burn wound, NS normal skin, HZ healing zone; original magnification, 40×). c, d Boxed areas in a and b are shown at higher power (original magnification, 100×). e, f Boxed areas in c and d are shown at higher power (original magnification, 200×); red arrow indicates CXCR4+ cell