Phenotype analysis of CRISPR/Cas9 generated null mice for determining the contraceptive potential of the selected genes. Spint4/5 and Ces5a null mice show significant fertility defects; meanwhile, Spint3, Pp2d1, and Saxo1 null mice appear normal. Fertility (a–c), body and reproductive organ weights (d–f), and sperm parameters (g–i) were all measured between knockout (−/−) and littermate control [wild-type (+/+) and heterozygous (+/−)] mice as indicated. Bars represent mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.005. ns, not significant.