Study on motion behaviours of mammalian sperm in actual oviduct and novel development for morphological evolutionary dynamics

2015 Fiscal Year Final Research Report

• Project/Area Number: 26560204
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Biomedical engineering/Biomaterial science and engineering
• Research Institution: Yokohama National University
• Principal Investigator: Hyakutake Toru 横浜国立大学, 工学(系)研究科(研究院), 准教授 (20335582)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Keywords: 非ニュートン流体 / 精子鞭毛 / 画像解析

Outline of Final Research Achievements

We experimentally observed sperm motion in fluids with various fluid rheological properties and investigated the influence of varying the viscosity and whether the fluid was Newtonian or non-Newtonian on the sperm motility. We investigated the following parameters: the sperm velocity, the straight-line velocity and the amplitude from the trajectory, and the beat frequency from the fragellar movement. In a Newtonian fluid environment, as the viscosity increased, the motility of the sperm decreased. However, in a non-Newtonian fluid, the straight-line velocity and beat frequency were significantly higher than in a Newtonian fluid with comparable viscosity. As a result, the linearity of the sperm movement increased. Additionally, increasing the viscosity brought about large changes in the sperm flagellar shape.These results suggest that the bovine sperm has evolved to swim toward the egg as quickly as possible in the actual oviduct fluid, which is a high-viscosity non-Newtonian fluid.

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