Fertility is normal in KissPRKO male mice at 12 weeks and 6 months of age. A, Mean body weights of WT and KissPRKO males. B, Percentage of males successfully siring pups during the 11-week fertility assessment period at each age. C, Latency for female partner to deliver first litter after pairing. D–F, Mean number of litters, pups, and pups per litter (litter size) during the 11-week fertility assessment at each age. There were no genotype differences for any fertility measure between WT and KissPRKO males.