Female GnRH-Itgb1−/− mice exhibit delayed puberty and abnormal estrous cyclicity. a, Vaginal opening and time of the first estrus were examined daily from P21 as good indicators of puberty onset in rodents. Vaginal opening in GnRH-Itgb1−/− females was delayed by ∼6 d when compared with control females. Vaginal smears were prepared daily following vaginal opening, and the age at first estrus (defined by the presence of a majority of cornified epithelial cells) was recorded (n = 12 each group). First estrus was delayed by ∼10 d in GnRH-Itgb1−/− females. Data are represented as means ± SEM. n, number of animals; *p < 0.0001, unpaired Student's t test. b, Analysis of cumulative percentage of vaginal opening within the two groups. In control females, 100% of the mice displayed vaginal opening by the P28, whereas the entire population of GnRH-Itgb1−/− mice had vaginal opening by the P37. c, Analysis of cumulative percentage of the first estrus within the two groups. In control females, 100% of the mice had the first estrus by the P34, whereas the entire population of GnRH-Itgb1−/− mice entered puberty at the P44.