Fig. 10. Defective COC expansion, anovulation and luteinization of unruptured follicles in adult Zp3-Foxo3a Tg mice. Adult female mice were checked by vaginal smears for the estrous stage, which indicates approaching ovulation. To obtain preovulatory follicles or newly formed corpus luteum (CL), ovaries were collected 2-4 hours before ovulation, or 36-48 hours after ovulation. (A) A developed follicle of preovulatory size in the Tg mice, with defective cumulus oocyte complex (COC) expansion. Note the tightly packed cumulus cells (arrow). (B) A CL with a trapped oocyte (Oo, arrow) in the Tg mice. In total, 15 adult female Tg mice were analyzed and representative results are shown. (C,D) Immunostaining for progesterone receptor (PR) in preovulatory follicles of WT (C, arrow) and Tg (D, arrow) mice. The experiments were repeated three times and representative results are shown.