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Scientific reports2018; 8(1); 16897; doi: 10.1038/s41598-018-34973-9

Hyperactivated stallion spermatozoa fail to exhibit a rheotaxis-like behaviour, unlike other species.

Abstract: The journey of spermatozoa through the female genital tract is facilitated by rheotaxis, or the cell's preference to swim against a flow, as well as thigmotaxis, the wall tracking behaviour, which guides them to the site of fertilisation. The aim of this study was to characterise the rheotactic and thigmotactic response of stallion sperm within a microfluidic channel. Stallion sperm rheotaxis was assessed within the microfluidic channel with regard to: (i) A range of flow velocities, (ii) Varying media viscosity and (iii) Sperm hyperactivation. Sperm distribution across the microfluidic channel was also studied and compared to human and ram sperm. Stallion sperm progressed furthest at a velocity range of 10-30 µm/s, with an optimum velocity of 20 µm/s. A flow viscosity of 2.5cP or greater reduced sperm rheotaxis (P < 0.05). Stallion sperm that were hyperactivated were unable to exhibit rheotaxis within the microfluidic channel, whereas, both hyperactivated human and ram sperm did exhibit positive rheotaxis under the same conditions. The number of sperm swimming near the microfluidic channel walls was higher than in the microfluidic channel centre (P < 0.05). This is the first study to illustrate that stallion sperm are rheotactically responsive and increasing viscosity reduces this response. We also demonstrated that sperm are predominantly inclined to swim along a surface and uniquely, hyperactivated stallion sperm are non-progressive and do not exhibit a rheotactic response unlike other species.
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Publication Date: 2018-11-15 PubMed ID: 30442996PubMed Central: PMC6237856DOI: 10.1038/s41598-018-34973-9Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research examines how stallion sperm behave under different conditions in a microfluidic channel, specifically investigating their rheotactic and thigmotactic response. Notably, unlike the sperm of other species, hyperactivated stallion sperm fail to show a rheotactic response—swimming against the flow, a characteristic previously seen as universal in sperm behavior.

Objective and Methodology

  • The study aims to understand the ways in which stallion sperm behave when challenged with different conditions within a microfluidic channel—a small, confined environment often used in studies like these.
  • The rheotactic and thigmotactic responses of the sperm were scrutinised, focusing on how several elements, including the flow velocity and viscosity of the surrounding medium, and sperm hyperactivation—when the sperm show increased mobility—affects their behaviour.
  • The research also compared the behavior of the stallion sperm with human and ram sperm under identical circumstances.

Key Findings

  • The researchers identified a specific velocity, namely 20 µm/s, where stallion sperm progress furthest, within the velocity range of 10-30 µm/s.
  • The results also indicate that an increased viscosity—above 2.5cP—in the surrounding medium significantly reduces the rheotactic response of the stallion sperm.
  • The most striking finding, however, is that hyperactivated stallion sperm do not show a rheotactic response, unlike what has been observed with other species’ sperms, such as human and ram. This essentially means that once hyperactivated, these sperm do not show preference for swimming against the flow.
  • In addition, it was found that sperm, generally, have a tendency to swim more near the microfluidic channel walls than in the center.

Significance of the Research

  • This study uniquely highlights the behavior of certain species of sperm, particularly stallions, under various conditions within a microfluidic channel.
  • Notably, it contradicts previously-held assumptions about hyperactivated sperm, at least where stallions are concerned, by demonstrating that they fail to show rheotactic behavior.
  • This could be a significant finding in reproductive biology and fertility research, as it adds nuance to our understanding of the factors that affect sperm mobility and, consequently, fertilization success.
  • The research could also influence future studies or technics aimed at manipulating or enhancing stallion sperm for breeding purposes.

Cite This Article

APA
Romero-Aguirregomezcorta J, Sugrue E, Martínez-Fresneda L, Newport D, Fair S. (2018). Hyperactivated stallion spermatozoa fail to exhibit a rheotaxis-like behaviour, unlike other species. Sci Rep, 8(1), 16897. https://doi.org/10.1038/s41598-018-34973-9

Publication

Scientific reports
ISSN: 2045-2322
NlmUniqueID: 101563288
Country: England
Language: English
Volume: 8
Issue: 1
Pages: 16897
PII: 16897

Researcher Affiliations

Romero-Aguirregomezcorta, Jon
  • Laboratory of Animal Reproduction, Department of Biological Sciences, School of Natural Sciences, Faculty of Science and Engineering, University of Limerick, Limerick, Ireland.
Sugrue, Emer
  • Laboratory of Animal Reproduction, Department of Biological Sciences, School of Natural Sciences, Faculty of Science and Engineering, University of Limerick, Limerick, Ireland.
Martínez-Fresneda, Lucía
  • Laboratory of Animal Reproduction, Department of Biological Sciences, School of Natural Sciences, Faculty of Science and Engineering, University of Limerick, Limerick, Ireland.
Newport, David
  • Bernal Institute, School of Engineering, University of Limerick, Limerick, Ireland.
Fair, Sean
  • Laboratory of Animal Reproduction, Department of Biological Sciences, School of Natural Sciences, Faculty of Science and Engineering, University of Limerick, Limerick, Ireland. sean.fair@ul.ie.

MeSH Terms

  • Animals
  • Biomechanical Phenomena
  • Chemotaxis
  • Freezing
  • Horses / physiology
  • Humans
  • Image Processing, Computer-Assisted
  • Male
  • Microfluidics
  • Rheology
  • Sheep
  • Sperm Motility / physiology
  • Spermatozoa / physiology
  • Viscosity

Conflict of Interest Statement

The authors declare no competing interests.

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Citations

This article has been cited 8 times.
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