Fig. 2. Oocyte-specific GCNF knockout mice display hypofertility, abnormal estrous cycle and double-oocyte follicles. (A) Reduced numbers of pups per litter and (B) reduced numbers of litters per month from the breeding of GCNF^fl/flZp3Cre⁺ females with wild-type males for 1 year. (C) Prolonged length of the estrous cycle in the GCNF^fl/flZp3Cre⁺ females. (D) Prolonged diestrus of the estrous cycle in the GCNF^fl/flZp3Cre⁺ females. (E) Normal ovarian histology except the presence of double oocyte follicles in the GCNF^fl/flZp3Cre⁺ females. (a) GCNF^+/+, (b) GCNF^fl/fl, (c) GCNF^fl/+Zp3Cre⁺ and (d) GCNF^fl/flZp3Cre⁺ ovaries were 3-month-old littermates. CL, corpus lutea. (e–h) The presence of double-oocyte follicles at the primary (e and f), secondary (g) and antral (h) stages in GCNF^fl/flZp3Cre⁺ ovaries. High magnification of the box in (d) is shown in (h). The bar scale in (a)–(d) is 200 µm. In (e)–(h) the bar scale is 50 µm.