Puberty and fertility assessment in BKO mice. (A) Percentage of mice undergoing vaginal opening over time. Inset shows day of vaginal opening [mean ± standard error of the mean (SEM)]. Flox mice are shown in white, and BKO mice are shown in green. (B) Female weights during puberty. Inset shows weight at vaginal opening (mean ± SEM). Asterisks indicate statistical significance for BKO versus Flox mice (*P < 0.05, **P < 0.01 by 2-way ANOVA). (C) Male body weights after weaning (mean ± SEM). (D) Six-week-old BKO and Flox mice were paired in different combinations and bred over a period of 6 months. Average days before the first litter was born to the breeding pair (mean ± SEM). Flox/Flox breeding is shown in white, BKO/BKO breeding is shown in green, and the mixed Flox/BKO breeding is shown in red and blue. (E) Average number of pups born to the indicated breeding pairs (mean ± SEM). Asterisk indicates statistical significance versus Flox:Flox (**P < 0.01 by ANOVA). (F) Number of litters over 6 months (mean ± SEM). Asterisk indicates statistical significance versus Flox:Flox (*P < 0.05 by ANOVA). (G) Days between litters over 6 months (mean ± SEM). VO, vaginal opening.