Loss of Fxyd1 expression delays female puberty in mice. A, Age at vaginal opening, B, Age at first oestrous, C, Age at delivery of first litter, D, Mating-delivery intervals for three consecutive litters delivered after the first litter. Bars are means and vertical lines are SEM. Numbers in parentheses on top of bars are number of animals per group. * = p<0.05, ** = p<0.02 vs. WT control.