Functional Regulation of Migrating Sperm in the Mouse Oviduct

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K06241
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 44020:Developmental biology-related
• Research Institution: University of Tsukuba
• Principal Investigator: BABA Tadashi 筑波大学, 生命環境系, 教授 (40165056)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 卵管 / 精子 / 受精能獲得 / マウス / 受精

Outline of Final Research Achievements

To accomplish fertilization in the ampulla of oviduct, ejaculated sperm are required to migrate through the female reproductive tract. However, this fundamental process largely remains unknown. The purpose of this work was to elucidate the mechanism that regulates the function of mouse sperm during the migration in the oviduct. After natural mating, sperm were abundantly present in the utero-tubal junction. As sperm approached the ampulla, the number of sperm dramatically decreased; the sperm numbers in the isthmus and ampulla were found to be approximately 100 and 10-20, respectively. Thus, the transport of sperm from the utero-tubal junction to the isthmus may be mainly dependent on oviduct fluid flows generated by contractions, and the sperm migration may be switched by the sperm motility near the ampulla. Importantly, only a single acrosome-reacted sperm was located close to an unfertilized oocyte in the ampulla.

Free Research Field

生殖生物学

Academic Significance and Societal Importance of the Research Achievements

顕微授精に代表される生殖補助技術の発展によって、雌性生殖管を経由しない精子でも産子が誕生することが証明された。このことを契機として、雌性生殖管での精子の機能制御に生理的意義がないような錯覚が広がっている。本研究では、生殖補助技術によってバイパスされた卵管で起こる仕組みを明らかにしていくところに高い学術的意義がある。加えて、ヒトや家畜・野生動物での生殖技術改善、避妊薬開発などの新しい技術開発への波及効果も期待できる。