Fig. 2
From: Heat Stress During Gametogenesis Irreversibly Damages Female Reproductive Organ in Rice
Early embryo sac development in IR64 plants exposed to control temperature (30 °C) during gametogenesis stage for 6 days. AN, antipodal cells; EC, egg cell; MMC, megaspore mother cell; PN, polar nucleus; SY, synergid. (A) A rectangle-like megasporocyte with inner and outer integuments; (B) Four megaspores linearly arranged after meiosis; (C) Degeneration of two megaspores (yellow arrow indicates the degenerated megaspores and white arrow shows active megaspores); (D) Degeneration of three megaspores (white arrow indicates the remaining functional megaspore); (E) A two-nucleate embryo sac; (F) A four-nucleate embryo sac; (G) An early stage eight-nucleate embryo sac; and (H) Middle stage of eight-nucleate embryo sac development, two polar nuclei have migrated to the central region and egg cell located near the micropylar region