Histological assessment of interstitial fibrosis and peritubular capillary density and detection of myofibroblasts in the obstructed kidneys of wild-type mice with either Agtr1^–/– marrow or Agtr1^+/+ marrow. Masson trichrome staining of the renal cortex at day 14 after UUO (a), immunohistochemical assessment of peritubular capillary density by immunostaining with anti-CD31 antibody at day 5 after UUO (b), and detection of myofibroblasts by immunostaining with anti-αSMA antibody at day14 after UUO (c) in mice with Agtr1^–/– marrow (left) and mice with Agtr1^+/+ marrow (right). Magnification, ×400.