(a–d) Upper panels: representative light micrographs of immunodetection of collagen I, III, IV, and fibronectin expression within kidney sections from B2+/+ and B2–/– mice either sham-operated or UUO for 5 days. Lower panels, corresponding quantitative analysis of collagen I, III, IV, and fibronectin expression. Data are expressed as the mean ± SD percentage of the interstitial area stained; n = 10; *P < 0.05 compared with respective sham-operated mice. ‡P < 0.05 compared with obstructed B2+/+ mice. Original magnification ×400.