Figure 2. Estrogen induces meiotic differentiation of OSCs in vitro. (A) CHiP-PCR analysis of ERα association with a consensus ERE in the Stra8 promoter in OSCs cultured without or with E2 (10 nM) for 1, 4 or 6 hours, using anti-ERα–based immunoprecipitation. (B) Confirmation of the specificity of the anti-ERα–based immunoprecipitation by pretreatment of OSCs with vehicle (V) or the pure ER antagonist, fulvestrant (Ful), prior to exposure to 10-nM E2 for 4 hours. See Figure 9A for additional data on fulvestrant. (C) Changes in Stra8 mRNA levels in OSCs cultured with vehicle (V), E2 (10 nM), P4 (2 μM) or E2 plus P4 for 24 hours (mean ± SEM, n = 3 independent cultures; *P<0.05). (D) Number of IVD-oocytes formed by OSCs treated with V, E2, P4 or E2 plus P4 for 24, 48 or 72 hours (mean ± SEM, n = 3 independent cultures; *P<0.05). (E) Numbers of OSCs, seeded at an initial density of 2 X 104 cells per well, through 72 hours of culture with V, E2, P4 or E2 plus P4.