title: Retinoic acid derived from the fetal ovary initiates meiosis in mouse germ cells.
abstract: Meiotic initiation of germ cells at 13.5 dpc (days post-coitus) indicates female sex determination in mice. Recent studies reveal that mesonephroi-derived retinoic acid (RA) is the key signal for induction of meiosis. However, whether the mesonephroi is dispensable for meiosis is unclear and the role of the ovary in this meiotic process remains to be clarified. This study provides data that RA derived from fetal ovaries is sufficient to induce germ cell meiosis in a fetal ovary culture system. When fetal ovaries were collected from 11.5 to 13.5 dpc fetuses, isolated and cultured in vitro, germ cells enter meiosis in the absence of mesonephroi. To exclude RA sourcing from mesonephroi, 11.5 dpc urogenital ridges (UGRs; mesonephroi and ovary complexes) were treated with diethylaminobenzaldehyde (DEAB) to block retinaldehyde dehydrogenase (RALDH) activity in the mesonephros and the ovary. Meiosis occurred when DEAB was withdrawn and the mesonephros was removed 2 days later. Furthermore, RALDH1, rather than RALDH2, serves as the major RA synthetase in UGRs from 12.5 to 15.5 dpc. DEAB treatment to the ovary alone was able to block germ cell meiotic entry. We also found that exogenously supplied RA dose-dependently reduced germ cell numbers in ovaries by accelerating the entry into meiosis. These results suggest that ovary-derived RA is responsible for meiosis initiation.
authors.affiliation: State Key Laboratory of Agro-biotechnology, College of Biological Science, China Agricultural University, Beijing, China.
authors.forename: Xinyi
authors.initials: X
authors.lastname: Mu
authors.forename: Jing
authors.initials: J
authors.lastname: Wen
authors.forename: Meng
authors.initials: M
authors.lastname: Guo
authors.forename: Jianwei
authors.initials: J
authors.lastname: Wang
authors.forename: Ge
authors.initials: G
authors.lastname: Li
authors.forename: Zhengpin
authors.initials: Z
authors.lastname: Wang
authors.forename: Yijing
authors.initials: Y
authors.lastname: Wang
authors.forename: Zhen
authors.initials: Z
authors.lastname: Teng
authors.forename: Yan
authors.initials: Y
authors.lastname: Cui
authors.forename: Guoliang
authors.initials: G
authors.lastname: Xia
mesh_terms: D000080924:Aldehyde Dehydrogenase 1 Family; D000818:Animals; D001547:Benzaldehydes / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D008297:Male; D008540:Meiosis / Q000502:physiology*; D008650:Mesonephros / Q000187:drug effects / Q000196:embryology / Q000502:physiology; D051379:Mice; D010053:Ovary / Q000187:drug effects / Q000196:embryology* / Q000502:physiology*; D010063:Ovum / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D011247:Pregnancy; D050697:Retinal Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism; D019849:Sex Determination Processes / Q000502:physiology; D046509:Tissue Culture Techniques; D014212:Tretinoin / Q000008:administration & dosage / Q000502:physiology*
chemical_list: D001547:Benzaldehydes; D004791:Enzyme Inhibitors; D007527:Isoenzymes; C055506:4-(diethylamino)benzaldehyde; D014212:Tretinoin; D000080924:Aldehyde Dehydrogenase 1 Family; C515028:ALDH1A1 protein, mouse; D050697:Retinal Dehydrogenase