Sperm Motility: Models for Dynamic Behavior in Complex Environments

Simons, Julie; Olson, Sarah D.

doi:10.1007/978-3-319-96842-1_7

Cited by 10 publications

(10 citation statements)

References 199 publications

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“…In addition, while elastic effects are relatively limited in methylcellulose solutions [10], which were used in both the observational human and sea urchin sperm studies considered here [10,11], elasticity is often extensive in physiological media [71,72] and may act to favour the concentration of large amplitude bending waves at the end-piece region [60] and warrants further study. Similarly, incorporating non-local hydrodynamic interactions [23,35,36,73,74] is likely to refine predicted waveforms, possibly further reducing the tendency to symmetry break [73], though this would require careful consideration of sperm head elastohydrodynamic boundary conditions.…”

Section: Discussionmentioning

confidence: 99%

“…A variety of derivations of active elastohydrodynamic systems have been presented in the literature, and thus these are not reproduced here. Instead, we direct the reader to excellent discussions and detailed derivations in [12,19,25,29,31,32,[34][35][36][37][38] and their appendices. Empirical estimates of the effective sliding moment density [4], resulting from the coupling between the dynein molecular motor activity and the passive cross-linking proteins within the flagellum [10,16,[39][40][41], indicate that the observed flagellar waveform of human sperm migrating in high-viscosity fluid can be captured by a simple travelling wave of dynein contraction, with a single characteristic frequency and approximately constant magnitude along the flagellum length [10,42,43].…”

Section: Flagellar Ultrastructure Elastohydrodynamic Formulationmentioning

confidence: 99%

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Flagellar ultrastructure suppresses buckling instabilities and enables mammalian sperm navigation in high-viscosity media

Gadêlha

Gaffney

2019

J. R. Soc. Interface.

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Eukaryotic flagellar swimming is driven by a slender motile unit, the axoneme, which possesses an internal structure that is essentially conserved in a tremendous diversity of sperm. Mammalian sperm, however, which are internal fertilizers, also exhibit distinctive accessory structures that further dress the axoneme and alter its mechanical response. This raises the following two fundamental questions. What is the functional significance of these structures? How do they affect the flagellar waveform and ultimately cell swimming? Hence we build on previous work to develop a mathematical mechanical model of a virtual human sperm to examine the impact of mammalian sperm accessory structures on flagellar dynamics and motility. Our findings demonstrate that the accessory structures reinforce the flagellum, preventing waveform compression and symmetry-breaking buckling instabilities when the viscosity of the surrounding medium is increased. This is in agreement with previous observations of internal and external fertilizers, such as human and sea urchin spermatozoa. In turn, possession of accessory structures entails that the progressive motion during a flagellar beat cycle can be enhanced as viscosity is increased within physiological bounds. Hence the flagella of internal fertilizers, complete with accessory structures, are predicted to be advantageous in viscous physiological media compared with watery media for the fundamental role of delivering a genetic payload to the egg.

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Section: Discussionmentioning

confidence: 99%

Section: Flagellar Ultrastructure Elastohydrodynamic Formulationmentioning

confidence: 99%

Flagellar ultrastructure suppresses buckling instabilities and enables mammalian sperm navigation in high-viscosity media

Gadêlha

Gaffney

2019

J. R. Soc. Interface.

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“…Moreover, individuals whose sperm swims relatively quickly in one experimental medium tend to also swim quickly in other media [34,74], suggesting that a morphology-speed relationship present in one medium might also be expected in the other(s), as seen in [11]. Although additional insights may be obtained by correlating the speed and morphology of individual sperm cells [9], overall, empirical studies in passerines do not provide support for sperm morphology-motility relationships predicted from hydrodynamic models of mammalian-like sperm [15,17].…”

Section: Sperm Morphology-motility Relationships In Passerinesmentioning

confidence: 94%

“…Instead, models suggest that swimming performance should be more directly impacted by the relative length of the flagellum (which produces forward thrust in the models by beating back-andforth or in a helical motion) compared to the head (which is thought to only produce drag, proportional to its surface area, [15]). This hypothesis is based on a large body of literature on hydrodynamic models that recognize that, at the scale and speed of sperm cells, viscosity has a vastly greater effect than inertia, such that a cell almost instantly stops making forward progress when it ceases actively swimming [15][16][17]. Several comparative [18,19] and intraspecific [20,21] studies support the hypothesis that a higher flagellum:head ratio increases swimming speed, although contradictory patterns have also been found [11,22].…”

Section: Introductionmentioning

confidence: 99%

Longer Sperm Swim More Slowly in the Canary Islands Chiffchaff

Cramer

Garcia‐del‐Rey

Johannessen

et al. 2021

Cells

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Sperm swimming performance affects male fertilization success, particularly in species with high sperm competition. Understanding how sperm morphology impacts swimming performance is therefore important. Sperm swimming speed is hypothesized to increase with total sperm length, relative flagellum length (with the flagellum generating forward thrust), and relative midpiece length (as the midpiece contains the mitochondria). We tested these hypotheses and tested for divergence in sperm traits in five island populations of Canary Islands chiffchaff (Phylloscopus canariensis). We confirmed incipient mitochondrial DNA differentiation between Gran Canaria and the other islands. Sperm swimming speed correlated negatively with total sperm length, did not correlate with relative flagellum length, and correlated negatively with relative midpiece length (for Gran Canaria only). The proportion of motile cells increased with relative flagellum length on Gran Canaria only. Sperm morphology was similar across islands. We thus add to a growing number of studies on passerine birds that do not support sperm morphology–swimming speed hypotheses. We suggest that the swimming mechanics of passerine sperm are sufficiently different from mammalian sperm that predictions from mammalian hydrodynamic models should no longer be applied for this taxon. While both sperm morphology and sperm swimming speed are likely under selection in passerines, the relationship between them requires further elucidation.

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“…The mathematical modelling of individual sperm cells has been well documented in recent reviews [26,27] and we summarize the topic here. More general information on the physics of microscale swimming is presented in [28][29][30].…”

Section: (B) Modelling Individual Sperm Cellsmentioning

confidence: 99%

Collective dynamics of sperm cells

Schoeller

Holt

Keaveny

2020

Phil. Trans. R. Soc. B

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While only a single sperm may fertilize the egg, getting to the egg can be facilitated, and possibly enhanced, by sperm group dynamics. Examples range from the trains formed by wood mouse sperm to the bundles exhibited by echidna sperm. In addition, observations of wave-like patterns exhibited by ram semen are used to score prospective sample fertility for artificial insemination in agriculture. In this review, we discuss these experimental observations of collective dynamics, as well as describe recent mechanistic models that link the motion of individual sperm cells and their flagella to observed collective dynamics. Establishing this link in models involves negotiating the disparate time- and length scales involved, typically separated by a factor of 1000, to capture the dynamics at the greatest length scales affected by mechanisms at the shortest time scales. Finally, we provide some outlook on the subject, in particular, the open questions regarding how collective dynamics impacts fertility. This article is part of the theme issue ‘Multi-scale analysis and modelling of collective migration in biological systems’.

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Sperm Motility: Models for Dynamic Behavior in Complex Environments

Cited by 10 publications

References 199 publications

Flagellar ultrastructure suppresses buckling instabilities and enables mammalian sperm navigation in high-viscosity media

Flagellar ultrastructure suppresses buckling instabilities and enables mammalian sperm navigation in high-viscosity media

Longer Sperm Swim More Slowly in the Canary Islands Chiffchaff

Collective dynamics of sperm cells

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