Figure 5. Failure of NPPC-induced attraction and artificial insemination of spermatozoa from Npr2^cn-2J/Npr2^cn-2J mutant mice.

(a and b) Accumulation of spermatozoa in the capillaries of NPR2 heterozygous and mutant males (a) and in the oviductal ampullae (b). Bars indicate the mean ± SEM of three experiments, each repeated twice per group. **P < 0.01, ***P < 0.001. (c) Representative spermatozoon micrographs of NPR2 mutant mice without or with 0.1 nM NPPC incubation for 1 min. Scale bars, 20 μm. (d) Comparison of normalized mean fluorescence intensity response (ΔF/F₀) in the sperm head and flagellar midpiece of NPR2 mutant mice after different treatments. Bars indicate the mean ± SEM of four experiments. n, number of spermatozoa for each bar. (e) Images of two-cell embryos after artificial insemination with spermatozoa from NPR2 heterozygous and mutant mice. Embryos and presumptive zygotes were collected from the oviducts 36 h after artificial insemination. Scale bar, 50 μm. (f) Percentages of two-cell embryo using spermatozoa of NPR2 heterozygous and mutant males. Bars indicate mean ± SEM of three experiments, each repeated four times per group. n, number of embryos and presumptive zygotes examined. ***P < 0.001.