Abstract
Sperm motion near surfaces plays a crucial role in fertilization, but the nature of this motion has not been resolved. Using total internal reflection fluorescence microscopy, we selectively imaged motile human and bull sperm located within one micron of a surface, revealing a distinct two-dimensional (2D) ‘slither' swimming mode whereby the full cell length (50–80 μm) is confined within 1 μm of a surface. This behaviour is distinct from bulk and near-wall swimming modes where the flagellar wave is helical and the head continuously rotates. The slither mode is intermittent (∼1 s, ∼70 μm), and in human sperm, is observed only for viscosities over 20 mPa·s. Bull sperm are slower in this surface-confined swimming mode, owing to a decrease in their flagellar wave amplitude. In contrast, human sperm are ∼50% faster—suggesting a strategy that is well suited to the highly viscous and confined lumen within the human fallopian tube.
Highlights
Sperm motion near surfaces plays a crucial role in fertilization, but the nature of this motion has not been resolved
We find that bull sperm exhibit this swimming mode even in low-viscosity media; for human sperm, slither swimming is prevalent only at higher viscosities (420 mPa Á s)
Both human and bull sperm were imaged in bulk liquid and near the wall with epifluorescence and total internal reflection fluorescence (TIRF) microscopy, respectively (Fig. 1a; Methods)
Summary
Sperm motion near surfaces plays a crucial role in fertilization, but the nature of this motion has not been resolved. Using total internal reflection fluorescence microscopy, we selectively imaged motile human and bull sperm located within one micron of a surface, revealing a distinct two-dimensional (2D) ‘slither’ swimming mode whereby the full cell length (50–80 mm) is confined within 1 mm of a surface This behaviour is distinct from bulk and near-wall swimming modes where the flagellar wave is helical and the head continuously rotates. Sperm must traverse thousands of body lengths in the complex three-dimensional (3D) female reproductive tract to reach the egg[1] During this journey, sperm exhibit a variety of motility modes (that is, motile, non-motile or hyperactivated) and swimming patterns (that is, typical, helical, hyper-helical, hyper-activated or chiral ribbons)—all of which are 3D in nature[2,3]. These findings indicate a distinct surface-confined sperm swimming mode that is well suited to the highly viscous and confined regions of the reproductive tract
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
