Fetal DA constriction following acute isoform-selective or nonselective COX inhibition on gestation day 18. (a) Incidence (no. constricted/no. analyzed) of fetal DA constriction following treatment with COX inhibitors indomethacin (indo), celecoxib (cel), SC-236 (236), and SC-560 (560). *Significantly different from incidence in vehicle-treated mice. P < 0.01, n ≥ 6. (b–g) Histology of mouse DA after a single inhibitor treatment. (b) Vehicle. (c) Dual COX isoform inhibitor indomethacin, 20 mg/kg. (d) COX-2–selective inhibitor celecoxib, 20 mg/kg. (e) COX-2–selective inhibitor SC-236, 20 mg/kg. (f) COX-1–selective inhibitor SC-560, 20 mg/kg. (g) SC-560, 50 mg/kg. Ao, descending aorta. Scale bar, 100 μm.