Blood vessel patency in mice exposed to hyperoxia. (A-H) Combined GS lectin staining (green) and ConA perfusion staining (red) (A,C,E,G) and ConA perfusion staining (B,D,F,H) of the retinal vasculature treated with Fc (A-B,E-F) or Dll4-Fc (C-D,G-H) for 24 hours followed by high oxygen exposure for 6 hours (A-D) or 24 hours (E-H). (I) Quantification of nonperfused areas per retinal quadrant; percentages indicate decrease of nonperfused area. (J-M) Combined GS lectin staining (green), ConA perfusion staining (red), and annexin V labeling (white, arrows). Six hours (J-K) and 16 hours (L-M) of hypoxia. Original magnifications: A-D, ×100; E-H, × 40; and J-L, ×400.