Activation of folliculogenesis by xenotransplantation with the immunodeficient animals

2022 Fiscal Year Final Research Report

• Project/Area Number: 17K15055
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Conservation of biological resources
• Research Institution: Kyoto University
• Principal Investigator: Fujihara Mayako 京都大学, 野生動物研究センター, 特定准教授 (00794504)
• Project Period (FY): 2017-04-01 – 2023-03-31
• Keywords: 卵巣 / 卵子 / 卵胞発育 / 野生動物 / 移植 / 保全

Outline of Final Research Achievements

Aiming to develop assisted reproductive technologies for the conservation of endangered animals, this study investigated a method for inducing the development of primordial follicles by transplanting ovarian tissue into immunodeficient animals using dogs and cats as models of wild carnivores. As a result of transplanting frozen canine ovarian tissue into immunocompromised rats, we demonstrated that ovarian tissue can induce follicle development from primordial to secondary follicles after 9 weeks of transplantation and that the ovarian tissue can be cryopreserved while retaining follicle development ability. To apply these results to wild animals, we are also promoting the "Ovarian Bank," which cryopreserves ovarian tissue and oocytes from wild animals. In addition, to extend the target species into birds, I have developed a cryopreservation technique to preserve oocytes in chickens, and am working on the application of this technique to endangered avian species in Japan.

Free Research Field

保全生殖学

Academic Significance and Societal Importance of the Research Achievements

希少動物の保全に生殖介助技術を用いる取り組みはこれまでも行われてきたが、未だ全ての雌の受精能力を保存する方法は確立されていない。本研究は凍結した卵巣内の未成熟な生殖細胞を周辺環境ごと他の動物種体内で体外発育させられることを示すもので、性成熟段階や繁殖周期を問わず、雌の卵巣から体外受精可能な卵子を獲得できることを示唆する。これは、幼弱期に死亡する例の多い野生動物の雌の配偶子も保存・繁殖活用できる可能性を示しており、実際に「卵巣バンク」として国内希少種を含めた野生動物の卵巣組織保存・蓄積にも取り組みも進めており、社会的関心の高い野生動物保全へ貢献する成果である。