Meiotic resumption of oocytes developed in vitro from mouse fetal gonads

To investigate the developmental competence in vitro of female germ cells in fetal gonads, gonadal ridges of 12.5 days post coitus (dpc) were organ-cultured for 18 days, and then oocyte-granulosa cell complexes (OGCs) were isolated from the cultures. Collected OGCs were further cultured for 11 days. The oocytes grown in vitro reached 64.1 ± 0.4 μm. Transmission electron microscopy analysis showed that oocytes grown in vitro had maintained connection with surrounding somatic cells. Some oocytes resumed meiosis by 1 μM okadaic acid or 10 ng/ml epidermal growth factor (EGF). The oocytes that underwent germinal vesicle breakdown reached 71.3 ± 0.5 μm. This study showed growth and meiotic resumption in vitro of oocytes through the support of ovarian tissue from fetal gonads.