1Disruption of the Endothelial Nitric Oxide Synthase gene affects ovulation, fertilization and early embryo survival in a knockout mouse model

Two consecutive experiments determined whether disruption of the endothelial NOS (NOS3) gene affects ovulation, fertilization, implantation and embryo development. In the first trial, Nos3-knockout mice (groups Nos3-/-) and wild-type mice (groups Nos3+/+) showed significant differences in mean number of corpora lutea (9.7 ± 1.2 in Nos3-/- vs 14.2 ± 1.2 in Nos3+/+; P < 0.01), rate of anovulation (48.3 ± 7.3 % in Nos3-/- vs 29.7 ± 6.3 in Nos3+/+; P < 0.05), total mean number of recovered oocytes/zygotes (4.0 ± 1.1 in Nos3-/- vs 10.4 ± 1.6 in Nos3+/+; P < 0.01) and non-fertilization rate (50.7 in Nos3-/- vs 3.3 % in Nos3+/+; P < 0.001). In the second trial, implantation and early pregnancy losses in Nos3-knockout and wild-type dams were detected by real-time ultrasound imaging. The number of embryos reaching implantation was higher in Nos3+/+ than in Nos3-/- mice (7.5 ± 0.4 vs 4.0 ± 0.4; P < 0.005); thereafter, embryo losses were detected between Days 8.5 and 13.5, in 62.5 % of the Nos3-knockout dams and, at Days 10.5 and 11.5, in 16.7 % of the control females (P < 0.005). Thus, NO and NOS3 deficiencies affec